Detective Diane Webb was determined. The Grim Sleeper, an anonymous killer who'd stopped murdering for 13 years, had resurfaced, and she had a plan for tripping him up. It was the fall of 2008, and she happened to show Detective Lauren Rauch, one of 33 officers who work for Webb monitoring the city's vast population of registered sex offenders, a recent L.A. Weekly news story headlined, "The Grim Sleeper: The most elusive serial killer west of the Mississippi took a 13-year break. Now he's back, murdering Angelenos, as cops hunt his DNA."

Webb, a hardcore number-cruncher and sex-crimes expert, floated an idea to Rauch and a few other cops in Parker Center.

What if she designed a special database search of the city's 5,212 registered sex offenders - enough bad seeds and creeps to populate a small town - that could pinpoint those men who fit the Grim Sleeper profile, and from that list try to determine whether any had avoided the required DNA test? What if a DNA match to the Grim Sleeper was, in essence, hiding in the data?

Rauch remembers how resolutely Webb told him, "We have to ID this guy. He is still out there somewhere. We need to ... collect samples from everyone."

She also ran her idea by a familiar LAPD figure, Dennis Kilcoyne, who is supervisor of the special task force that has been searching for the Grim Sleeper. "It was her belief that our guy could be one of those," lurking undiscovered in the files, says Kilcoyne, who told her he heartily backed her plan.

Webb - an Edie Falco look-alike - did not end up finding the Grim Sleeper in her long-shot quest. He wasn't there, in all those files. Instead, through tantalizing coincidences and teamwork that tapped the memories of long-retired cops, LAPD found the alleged serial killer The Westside Rapist, a man who had slipped away from the cops in 1957 and went on to terrorize elderly women in Southern California for a generation.

The state of California has required sex offenders to register since 1947, the year of the globally sensational Black Dahlia murder case. And Webb's team, called REACT (Registration Enforcement and Compliance Team), keeps tabs on where they are living and whether they are in trouble with the law.

Her number-crunching peek into the database quickly determined that 1,500 sex offenders fit the rough description of the Grim Sleeper: a black man who now would be middle-aged or older. Most importantly, deep in data, Webb confirmed a troubling anomaly that her gut had told her to expect: Ninety-two of the 1,500 had never been cheek-swabbed for DNA, as required by law.

If any of the 92 were killing or raping Angelenos, and leaving behind their sperm, saliva, blood, hair or other traces, they were doing so with impunity, invisible to the vast DNA-tracking system.

Webb, who spent years probing sex crimes in the City of Angels, has met more rape victims and rapists than the lead players in Law and Order: SVU and knows too well the sinister deeds perpetrated by humans upon their fellow humans. "Most people think registered sex offenders are under some formal supervision," says Webb. Not so. Only about a quarter are under parole oversight or other direct supervision.

You might say that Webb, who sports a feathered, blond bob, is obsessed with sex, though not in a twisted way. Like many former sex-crimes detectives, she's haunted by a specific case. In the early 1990s, a registered sex offender got out on parole, committed a series of rapes and then savagely attacked a young girl in Inglewood. Webb believes that if her REACT monitoring team had been in place then, that career pervert would have been noticed, picked up - stopped.

"I have always felt very badly that this guy wasn't caught sooner, when it could have been possible," she says.

When Webb ordered her massive manhunt last fall for the 92 unswabbed men who might include the Grim Sleeper, she couldn't have known that hers was the final act in a series of decisions by detectives stretching over three decades, in what amounts to one of the longest-running manhunts in L.A. history. Without these independent acts, from Detective Larry Manchester's quirky 1970s decision to save trace evidence after reading about newfangled "DNA science" to a random decision by cold-case detective Richard Bengtson in 2002 to reopen Manchester's unsolved Elizabeth McKeown murder case, suspected Westside Rapist John Floyd Thomas would not be safely locked away.

Last October 22, Thomas, a gregarious state workers' compensation fund insurance adjuster, strolled into LAPD's Southwest Division wearing a red, long-sleeve dress shirt and slacks, to be tested for DNA as part of Webb's 92-man sweep. The one indication on Thomas' rap sheet that he deserved a far closer look was his single rape conviction for brutally assaulting the elderly Mrs. Stellern (her first name has never been released) in Pasadena in 1978; in his fury, he had snapped her ankle to the bone.

Thomas was instructed to scrape the inside of his mouth four times, front to back, and drop the swab in an envelope. The meeting was uneventful, says Officer Robert Lanigan. "It was pretty boring, really."

"He probably would have been the last person we would have suspected," adds Lanigan's partner, Amber McDonnell. "He looked professional and was very pleasant to deal with."

Five months later, that cheek swab was matched to five killings and rapes from the 1970s and '80s that featured the same, relatively odd, MO - all the victims were elderly white women, raped and then strangled. The cops had in their hands a rare, multiple DNA hit that strongly suggested an undetected serial killer.

As writer Michael Connelly's colorful fictional detective Harry Bosch would say, in murder, there are no coincidences. There are only connections that lead inexorably to other connections. The fax trumpeting the five DNA matches did not show up at Webb's Parker Center office in Room 333. Instead, it arrived two floors above her, where two cold-case cops she'd never met were working to find a long-ago killer-rapist.

In a room decorated with historic crime-scene photos - gifts from novelist James Ellroy - Richard Bengtson and Rick Jackson had been struggling to crack the murders of Elizabeth McKeown and Ethel Sokoloff, elderly women who, more than 30 years ago, were raped and strangled by an anonymous ghoul with an iron grip. After Bengtson reopened the McKeown case, retired Detective Larry Manchester began peddling his hunch that her slaying - Manchester's sole unsolved homicide during his LAPD career - was the work of an undetected serial murderer.

Now, here was an unexpected fax transmitting the long-elusive answer: John Floyd Thomas was their man.

Jackson immediately phoned Bengtson, a classic, gnarly cop, at home. Bengtson downplays this dramatic moment: "Maybe after [his] conviction, we will go to lunch or something."

In fact, for "closers" working on dusty, cold cases, this kind of multiple DNA hit is the Holy Grail. Webb's genius stroke had allowed LAPD to reach far across the years into the vague gloom of the 1950s, the decade in which the Westside Rapist apparently began his hideous career. Thomas is now charged with the murders of Elizabeth McKeown and Ethel Sokoloff. Officials also now say his DNA was left at the 1975 scene of the murder of 79-year-old Cora Perry in Lennox, and Thomas is also the menace who terrorized a single block in Claremont in the 1980s, first raping and killing Isabel Askew - and three years later returning to the same ill-fated apartment to rape and kill her daughter, Adrienne Askew. Inglewood police say Thomas' DNA also connects him to the 1976 murder of 80-year-old Maybelle Hudson.

Police believe he may be responsible for as many as 34 rapes and murders attributed to the Westside Rapist. Those whose lives were hijacked by this predator hope the right man is finally behind bars. Says Tracy Michaels, the great-niece of Elizabeth McKeown, who still mourns her beloved schoolmarm aunt, "It is a miracle to get an answer after all these years. There are two women in my family who are going to look in his eyes, and mine will be the second."

Hanging on the door of Parker Center Room 503, two floors above Diane Webb's own offices, is a framed paragraph from Michael Connelly's bestseller The Closers, in which Harry Bosch's new supervisor, Abel Pratt, explains: "This squad is the most noble place in the building. A city that forgets its murder victims is a city lost. This is where we don't forget. We're like the guys they bring in in the bottom of the ninth inning, to win or lose the game. The closers. If we can't do it, nobody can. If we blow it, the game is over because we're the last resort. Yes, we're outnumbered. We've got nine thousand open-unsolveds since 1960. But we are undaunted. ... We're the closers, baby."

The "unsolveds" still on file at LAPD stretch back into the 1800s. In a coincidence that proved prescient, Richard Bengtson's LAPD bosses in 2002 randomly assigned him to concentrate on a single year - 1976. From the many cold cases in 1976, Bengtson plucked the then-uncrackable Elizabeth McKeown murder.

Bengtson, a quiet, no-nonsense cop with a shy smile, says the case got under his skin. "It was an older lady. She could be your mom or grandmother. It stuck with me."

He didn't have much to go on, because in 1976 police rarely worried about saving trace evidence, which today is routinely subjected to DNA tests. But in a moment of synchronicity, one day Bengtson was digging around when he found a forgotten filing cabinet in a dank storage room at the Los Angeles County Department of Coroners. That cabinet turned out to be a treasure trove of forgotten but largely intact microscopic slides of semen, saliva and blood from scores of murder cases from 1972 to 1978.

The potentially game-changing microscopic evidence and DNA, involving hundreds of slides from old crimes, somehow "was not in [the coroner's or LAPD's] computer-based system. It was unaccounted for." Bengtson and his partner, Vivian Flores, painstakingly pored over the slides, but in the back of their minds, they had to have been thinking that detective work is too often about red herrings and false leads. What chance was there, really, that a jumbled bunch of forgotten slides would hold clues to the very crimes they were pursuing?

But incredibly, they hit pay dirt: DNA collected at the horrific crime scene where Elizabeth McKeown had been found dead had somehow survived on pieces of glass - for 26 years.

Then, in the summer of 2003, long-retired cop Larry Manchester was drawn back into the McKeown case, thanks to yet another peculiar coincidence, which ultimately helped to snag John Thomas. Manchester was set to play a solo round of golf at the Mile Square Park Golf course, when he was paired with retired Los Angeles County Sheriff's homicide detective Bill Stoner. Stoner had been featured prominently in James Ellroy's 1996 crime memoir, My Dark Places, about Ellroy's hunt for the man who murdered his mother in Los Angeles in 1947 - a crime that remains unsolved.

As they golfed, Manchester told Stoner about Elizabeth McKeown, the long-unsolved case that clearly nagged at him. Stoner traded stories, telling Manchester about similar attacks on elderly white women in Lennox, also in the 1970s. Stoner urged Manchester to contact Detective Rick Jackson, a friend of James Ellroy's - and a legend at Robbery Homicide downtown.

The universe of elite homicide detectives isn't very big. As it turned out, Manchester knew Rick Jackson. The two were temporarily partners in 1988 and sent by LAPD to Plattsburgh, New York, to transport back to Los Angeles two Russian immigrants standing trial for the murder of an elderly North Hollywood couple.

Intrigued by Stoner's information, Manchester contacted Jackson at LAPD's cold-case unit to share his theory that Elizabeth McKeown had been killed by an as-yet-undetected serial murderer active in Inglewood and Lennox. Jackson alerted his cold-case colleague Bengtson, sitting a few desks away, and suddenly, another piece in the unfolding series of coincidences slid into place: Bengtson, Jackson marvels, "happened to have [the McKeown case] on his desk. Of all the thousands of cases we were reviewing. What a small world."

Rick Jackson had retired from the LAPD in 1996 and moved to New Hampshire, where, Manchester quips, "there is no sales tax." But Jackson didn't take any better to retirement than the fictional Harry Bosch had. In fact, it was thanks to Jackson that Connelly's detective character was brought back from life support in 2005. At the time, Connelly feared he may have "doomed" his bestselling murder series by turning the brilliant but loose-cannon cop into a private detective on the outs with LAPD. After writing two novels in which Bosch works for hire, "I felt that routine would make me lose interest and the series would die," Connelly told a newspaper.

The author didn't know how to rescue Bosch from himself. But then, by coincidence, he heard the true tale of Rick Jackson's escape to woodsy New Hampshire, and his return to LAPD. Hearing of Jackson's successful re-entry into policing gave Connelly the idea that he could do the same with Bosch. Connelly told the interviewer, "It was just what I needed right when I was struggling - and was told Harry could come back."

After Jackson shared Larry Manchester's theory that Elizabeth McKeown was one in a series of killings by the same man, Richard Bengtson ran hard with the idea, contacting Inglewood police and seeking similar cases. Then, he got word from the LAPD criminologists that McKeown's killer had indeed left traces of his DNA at the scene of a similar crime, the rape and murder of 68-year-old Ethel Sokoloff right around Thanksgiving in 1972.

Just as with the Grim Sleeper case, LAPD had this killer's DNA. But they couldn't find a name or face in any criminal database to match it. Bengtson was hoping that California's new law, Proposition 69, which requires all felons to submit to a DNA cheek swab, would drag Sokoloff and McKeown's killer out of the shadows. Instead, he and Jackson got their break - and Manchester's nagging career quest was resolved - thanks to the woman working on the third floor at Parker Center, the dogged number-cruncher Diane Webb.

Webb, sitting near her computer, overlooked by her office talisman - a Gumby dressed in police blues - says nobody at police headquarters paused to congratulate her. There wasn't really time. A typical no-nonsense cop, she tries to undersell her role. "There was no big celebration." Instead, she felt, "We have work to do - this is great, there is a [DNA] hit. Now, let's investigate."

For retired detective Manchester, this tale began on a dark, chilly evening on February 18, 1976. A fresh, young homicide detective, his very first case was that of retired school administrator Elizabeth McKeown, whose half-naked body was found in her '65 Chevelle, not far from her small apartment in a neighborhood between Fox Hills and Westchester.

Manchester, now 64 and living in Reno, never got over the McKeown case. "She had never been married ... she was clean as the driven snow. She was in love, but the guy jilted her. She was crushed. It was pre-World War II. She wasn't able to establish another relationship of any substance."

Manchester says today, "I always thought I didn't want to die without finding out what had happened to [Elizabeth] McKeown."

Then a crucial coincidence occurred, the kind of thing that would give Harry Bosch pause: It was 1976, and Manchester saw a magazine article about the science of DNA technology. "It was something pretty new," Manchester says today. In fact, most cops then relied on crime-scene analysis as rudimentary as grade-school math: spraying Luminol to locate fingerprints, and identifying blood types and groups. Influenced by the fascinating magazine piece, Manchester did something odd for those times: He insisted that the Los Angeles County autopsy technicians save as much human detritus and trace evidence found at the McKeown crime scene as possible. His unusual request would prove instrumental in solving the dust-gathering case, retrieved from a police evidence shelf by Bengtson and his partner Vivian Flores three decades later.

On the February night she died, McKeown had returned home from an event at the Dorothy Chandler Pavilion. Later that evening, a witness saw someone driving McKeown's car erratically near her home. Another witness heard a dragging noise coming from her apartment - it went on for 30 minutes. Neither alerted police. "We don't want to get involved," chides McKeown's great-niece, Michaels. "That is the epitaph on a lot of people's gravesites."

A cluster of similar rape-murders had taken the lives of Cora Perry, 79, of Lennox, and Maybelle Hudson, 80, of Inglewood. "We had a meeting and I said, 'I think we have a serial killer,' ' recalls Manchester. "Right-hand strangulation, sex assault, older white women. His murder weapons were his hands, his powerful forearms."

It's odd that McKeown's case never ended up downtown at Parker Center, where an elite task force of homicide detectives was looking into a series of 22 rapes and 12 murders of elderly white women within a 20-square-mile area encompassing Hollywood. The so-called Westside Rapist attacks had begun in 1974 with the rape and murder of Ethyl Grimes in her Rampart home and seemed to taper off in 1976 with the strangulation of Hazel Nichols. As with McKeown's attacker, the suspect's MO included placing a blanket, pillow or clothing over victims' faces.

The task force focused on four suspects, including 19-year-old Brandon Tholmer, a handsome musician who was eventually convicted of raping an elderly woman in her home in 1976.

"They all lived within a mile of [Tholmer's] house," says In Cold Blog Web site publisher Corey Mitchell, who explains the Tholmer case in his book, Hollywood Death Scenes: True Crime and Tragedy in Paradise. "At 1 or 2 in the morning he would sneak his way in and beat the tar out of these ladies and rape them."

But Tholmer's strange MO - he liked to set fires and kill his victims' cats - did not fit with dozens of the unsolved cases. Over time, the extensive Westside Rapist sleuthing, and the related lore, became "famous in Robbery Homicide Division," says Bengtson. Next to his desk even today is a poster-sized chart labeled "Westside Rapists - Suspects Time Study Chart," created by a past era's stumped detectives. Their effort, "was along the lines of the Hillside Strangler," Bengtson says. "It was heartbreaking [to cops of that era] that it was never solved."

The Westside Rapist task force quietly disbanded in 1976, and detectives hoped that Tholmer was their man. But about two years later, another attack occurred on North Madison Street in Pasadena. On that dreadful night, Gary Stellern's feisty mother, born on April Fool's Day in 1900, had attended a lecture at Pasadena City College. When the retired social worker got home at 10:15 pm, an intruder wearing gloves tried to strangle her, snapped her ankle, savagely raped her and left her for dead. Her son Gary, now 75, still weeps when talking about getting her phone call for help that night.

Rushing over to her apartment, he found her sitting on the floor. "This is the part that burns my ass," he says today, crying openly. His mom "was a tough old bird. She wasn't crying. She had to have been in shock." Stellern later told police her attacker had "very strong hands."The next morning, a neighbor said he had seen a black man park his car and walk around the neighborhood, entering and then leaving Stellern's apartment courtyard. The neighbor had a habit of writing down unfamiliar license plate numbers. This time he jotted down the letters and numbers John 73. The plate number was registered to then-41-year-old salesman John Floyd Thomas Jr., who lived on nearby South El Molino Avenue. When police searched his blue Ford Mustang, they found dark clothing and a ski mask, and he was charged with the Stellern rape. Yet even as he faced trial, the friendly seeming Thomas somehow managed to marry Colette Webb, on April 5, 1978. Then, on August 17, 1978, a jury convicted him of rape, burglary and mayhem - for viciously snapping Stellern's leg.

Gary Stellern says the police "showed me [Thomas'] rap sheet. He had been busy" - in fact since 1957. (Please see sidebar.) That year, a crucial and deadly mistake by a county prosecutor allowed Thomas to get off lightly, and to spread his misery for years.

Thomas, at the time a 20-year-old county file clerk who had been dishonorably discharged from the Air Force, got arrested after breaking into a home on West 35th Place. He had climbed into an elderly woman's bed and ordered her to be quiet, but was shot by the woman's son-in-law after she screamed for help. Though injured, Thomas made it back to his apartment on nearby St. Andrew's Place - but his wife called an ambulance. His suspicious wound led to his arrest for attempted rape. Just a month earlier, police had tied Thomas to a rape and an attempted rape. Despite all that, a plea deal was offered by a lenient Los Angeles County prosecutor, and Thomas was convicted only of burglary.

For more than two decades after that, whenever police searched the files for rape suspects, Thomas' name did not appear. Because of the old plea deal slapping his hand for a mere burglary, Thomas escaped the post-Black Dahlia requirement to register as a sex offender. That was a disastrous misstep by the D.A., reverberating for 30 years, during which this predator apparently boldly repeated his murderous MO again and again. "The ball was dropped back in 1957," says a clearly bothered Manchester.

Thomas' known record, including the 1978 brutal rape and assault of Mrs. Stellern, did not seem to hinder his career, or alter his outward appearance as a normal guy. He did five years for raping Stellern, yet somehow, in 1983, he got a job as a hospital "peer counselor" in Chino. But finally, the cops noticed Thomas and he was forced to register with the San Bernardino County Sheriff as a sex offender on May 17, 1983.

Three months after Thomas was so belatedly placed on the sex-offender registry, Isabel Askew disappeared in Claremont, four miles from Thomas' home. Askew's body was found in a local vineyard. She had been raped.

In a harrowing drama over several years that nobody seemed able to stop, police now believe it was Thomas who returned again and again to wreak his havoc on the same Claremont block where Askew lived. In March 1986, an 83-year-old neighbor of Askew's was raped and robbed. The next month, a 78-year-old woman was attacked a few blocks north of Askew's apartment.

Then, in a case that few of the detectives will ever shake, in June 1986, Askew's 56-year-old daughter, Adrienne, was found strangled - in the very apartment from which her murdered mother vanished. DNA found at Adrienne Askew's murder scene 22 years ago has finally been matched to Thomas, who is also believed to have slain her mother years earlier.

Months later, in March 1987, Thomas - who had managed to link up with an unsuspecting girlfriend - became a father to a baby boy. He and his girlfriend married in April 1989 and returned to Los Angeles, where Thomas worked in the mailroom of the State Compensation Insurance Fund on Wilshire Boulevard near Fairfax Avenue.

That's when police believe his reign of terror finally ended. On July 1, 1995, the apparently dormant but oft-divorced Thomas walked down the aisle again, this time with Carolyn Moret.

One of Thomas' co-workers at the Wilshire offices of the insurance fund was Earl Ofari Hutchinson, a well-known political columnist. Hutchinson - like many others - describes Thomas as personable and congenial. Thomas had found religion and liked to send his colleagues e-mails full of biblical passages and inspirational notes. Hutchinson recalls: "The biblical passage was tied in with something for the day, like stay positive, or if you are having a challenging time, read a passage from Cornelius."

Hutchinson was amazed in those days by what great shape Thomas was in for a middle-aged guy. "I would say, 'What is the secret?' Thomas would chuckle and say, 'Just good living.' " Says Hutchinson, "He was always with women - a circle of female admirers - because he was so congenial."

Elizabeth McKeown's great niece, Tracy Michaels has long been haunted by the murder of her warm, wonderful aunt. In December 2007, she began talking to an old L.A. buddy about her planned memoir, and sent him a draft in February.

Her friend was astounded by the tragic chapter about her aunt. He offered to find out what had become of Elizabeth's unsolved murder, leading him to Detective Richard Bengtson. Michaels spoke to Bengtson on March 19 and says Bengtson told her: "'I want you to know something.' He said, 'We may never solve it, but I will never take it off my desk again. It will never be in a vault again.' And I knew they would solve it."

The next morning, Michaels opened a box she had gone through a hundred times, yet for the first time, she came across a picture of her Aunt Elizabeth, one she hadn't seen for 30 years. To her, its sudden appearance was a sign of hope.

On March 27, Rick Jackson got the call from the LAPD's crime lab that some DNA results were on the way. He had no idea the matches were the result of Diane Webb's sleuthing two floors below, to locate and swab the 92 untested men. "They said, 'Are you by a fax?' " Jackson remembers. When he saw that the matches looked like a huge break in the infamous McKeown case, "First thing I did was notify Rich [Bengtson], because it was his baby." The fax identified as the prime suspect John Floyd Thomas; his DNA had been found at five horrible murder scenes.

"I was probably in disbelief," says Bengtson.

They were stoked to very quickly determine that Thomas still lived here - and was even listed in the official sex-offender registry, which is found under the widely used Megan's Law service online. Within a day, undercover officers began surveillance on Thomas at his home in South Los Angeles.

Eerily, he was living just a few, short blocks from the original 1957 sexual attacks he'd committed as a young man, and which he'd manipulated the justice system and D.A. into treating as burglary. On March 31, officers took him to the main Robbery Homicide squad room in Parker Center, where he was interrogated for four hours. Richard Bengtson immediately noticed Thomas' firm handshake and iron grip. "He was very calm," says Bengtson. But "sometime during the interview, he became a little more nervous."

Rick Jackson called Larry Manchester to tell his old friend in Reno the stunning news. He asked the retired detective if he was sitting down, then asked, "Does the name Elizabeth mean anything to you?" Manchester's quirky decision in 1976 to save all that forensic evidence from the Elizabeth McKeown murder, all because he read a magazine article about newfangled DNA, had come full circle.

After he got off the phone, tough cop Manchester sobbed for several minutes. "The relief I felt was cathartic," he recalls.

Ofari Hutchinson says that many of Thomas' co-workers are still in denial. "Our John is accused of all these monstrous things?" he asks, repeating some of the reactions he's heard. Hutchison asked two of Thomas' female colleagues if they believed Thomas had committed these heinous crimes. "Hell, no!" they told him.

Hutchinson provided his own theory about the chameleonlike man with whom he worked. "There are two different people. You have this accused mass murderer-rapist-insane guy and now you have this whole other guy who found spiritualism. This guy wouldn't recognize the John of 20 years ago.

"How could he fool me?" Hutchinson asks. "He didn't. I saw a different person. It was a whole other John."

The bittersweet news of Thomas' capture quickly made its way to Tracy Michaels. "Bengtson called to tell me the LAPD had arrested the man who they are absolutely certain killed [my aunt]. Even listening to him, I was somehow very aware that my whole family was hearing this news with me."

The story isn't over. Bengtson and Jackson are now probing whether Thomas is linked to more than 30 Westside Rapist and other unsolved cases. In many instances, the DNA has been denigrated or the old forensic evidence tossed out. Bengtson has received more than 40 calls from people who believe their loved ones or friends are Thomas' victims.

Webb, for her part, was not formally alerted that her plan to cull the 1,500 men in search of the Grim Sleeper had, by some dark serendipity, caught a different high-profile psycho in its web. She got no awards plaque and received no flowers. She had simply done her job, and she heard the news, not from Bengtson or Jackson, but through the police grapevine.

Dennis Kilcoyne, who heads up the LAPD search for the Grim Sleeper, is happy on one hand, but on the other, he's "disappointed it wasn't our guy. We are keeping our fingers crossed that lightning will strike twice on old [sex-offender] registrants."

The Grim Sleeper should still be worried. Innovator, number-cruncher, and world-class organizer Diane Webb is not yet done. She strongly suspects that if 92 guys ducked their required DNA swabs in the group she studied, dozens from a larger pool of sex offenders - those people who have moved from Los Angeles - may have also escaped the DNA net.

"We will get to the bottom of who may have slipped out of the swabbing," she says, matter-of-factly. Out there, somewhere, she holds out hope that another man who continually avoided his required swabs is quietly lurking.

Timeline of John. F. Thomas'

Key Rapes and Killings

March 1957: Raped a woman in South Los Angeles. Attempted five days later to rape another woman.
June 1957: Attempted to rape an elderly woman on West 35th Place but was shot by her son-in-law. Went to prison for five years on a greatly reduced "burglary" charge.
November 1972: Thomas' DNA was left at the murder of Ethel Sokoloff.
September 1975: Thomas' DNA was left at the murder of Cora Perry.
February 1976: Thomas' DNA was left at the murder of Elizabeth McKeown.
April 1976: Thomas' DNA was left at the murder of Maybelle Hudson.
June 1976: Believed to be the attacker of Miriam McKinley.
October 1976: Believed to be the attacker of Evalyn Bunner.
February 1978: Thomas raped and attempted to strangle Mrs. Stellern. Went to prison for five years.
August 1983: Released from prison, Thomas is believed to have raped and killed Isabel Askew in Claremont.
March and April 1986: Believed to have raped two of Isabel Askew's neighbors.
June 1986: Believed to have raped and killed victim Isabel Askew's daughter, Adrienne, in the same Claremont apartment where her murdered mother had lived.