San Diego County teenagers Chelsea King and Amber Dubois would probably be alive today if the state prisons agency had not repeatedly fumbled opportunities to put a convicted child molester back behind bars for violating parole, California's inspector general concludes in a new report today.

If state prison officials had been more diligent in supervising John Albert Gardner III, authorities could have revoked his parole, "making it impossible for him to murder the two young girls," State Inspector General David Shaw wrote in his probe results.

At least seven parole violations have been previously reported, but Shaw reveals a new one - that Gardner unlawfully entered the grounds of Donovan State Prison in San Diego County

Shaw's report and recommendations now go to the governor, prison authorities and lawmakers.

Gardner pleaded guilty to raping and murdering Chelsea, 17, of Poway and Amber, 14, of Escondido. He was sentenced on May 14 to two life terms without the possibility of parole.

In a cover letter to prisons Chief Matthew Cate, the inspector general bluntly said that parole agents failed to identify Gardner's "aberrant behavior" that included "numerous parole violations" that would have sent him back behind bars.

Shaw's 41-page report detailed a troubling pattern of errors in how the state's prison agency handled Gardner, finding particular fault with monitoring global positioning systems used to track sex offenders on parole.

Despite the tracking, Gardner was able to enter prison grounds briefly twice on July 12, 2008. Prison authorities indicated he did not have permission to be at the Donovan facility on Otay Mesa Road. Gardner, interviewed by investigators May 14, said he was dropping off a friend in the prison parking lot and then later picked her up.

But investigators noted that Gardner, who spent time at the prison during his first incarceration for molesting a Rancho Bernardo girl in 2000, was near an area that served as a path to move contraband at the minimum security site.

In his response, Cate, the prison's chief, noted that Gardner, who was discharged from parole before the crimes, was on "passive" monitoring. That means the parole agent had at least 39 others to track.

Subsequently, the state has discarded passive monitoring and now requires more intense tracking, even of those lower-risk offenders, Cate said.

"Moving forward, the department must take this experience and make every effort to detect every crime and violation possible, especially if doing so could reduce the likelihood of a future crime being committed," Cate wrote.

Significantly, Cate, who called Gardner a "monster," said "only a life sentence can eliminate the risks presented by a predator like Gardner."

Cate also defended parole agents, noting they "put their lives on the line every day because they care deeply about public safety."

Shaw, the inspector general, said the GPS system used by the corrections department "remains deficient" even after some March 2010 changes.

And Shaw warned that those changes, even if in effect before Gardner's crimes were committed, would not have saved the lives of Chelsea and Amber.

That new policy this year that expanded the use of GPS "limits the time that parole agents spend in the field by imposing on parole agents laborious GPS data review techniques."

Shaw made several recommendations, including assigning trained "criminal intelligence specialists" rather than parole agents to conduct the initial review of GPS tracking data. He also recommended that the state establish automatic alarms within the GPS system to alert authorities when a parolee violates conditions.

"Department records indicate that parole officials considered revoking Gardner's parole on seven different occasions," Shaw reported. "In each of these instances, Gardner was allowed to remain on parole rather than return to prison."

One of those violations, being on prison grounds, is a felony.

Also, the shredding of some central file material, which was routine practices at the time, hamstrung the investigation somewhat, Shaw wrote.

"We were unable to completely assess the department's adherence to its parole supervision policies," according to the report.