The Los Angeles police chief and district attorney are defending their exhibit of evidence from famous crimes including Sen. Robert F. Kennedy's assassination.

They released a letter Friday after Kennedy's son denounced them in a Los Angeles Times op-ed piece for planning to show the suit the senator wore when he was killed. Maxwell Kennedy called it "a macabre publicity stunt."

Chief Charlie Beck and District Attorney Steve Cooley say they never intended to compound the grief of murder victims' families. Beck and Cooley say they sought to depict the horror of homicide in hopes of deterring violence.

Thursday was the last day the exhibit was open to the public at a Las Vegas casino hotel. Police say thousands have waited in line as long as two hours to see it.

THIS IS A BREAKING NEWS UPDATE. AP's earlier story is below.

LOS ANGELES (AP) - The son of the late Sen. Robert F. Kennedy said he was "horrified" when he learned earlier this week that clothing that his father was wearing when he was assassinated in 1968 was being displayed at an exhibit in Las Vegas.

Maxwell Taylor Kennedy criticized the Los Angeles Police Department in a commentary prepared for Friday's Op-Ed page in the Los Angeles Times.

Maxwell Kennedy, a former assistant district attorney who lives in Los Angeles, called the display of his father's clothing "part of a macabre publicity stunt" and "a cheap bid for attention."

After a complaint from the family, the LAPD removed the items from a display at a homicide investigators conference in Las Vegas.

"This is supposed to be a learning experience," Police Chief Charlie Beck told The Associated Press on Wednesday. "It wasn't intended to cause anyone grief or to be prurient or salacious in any way."

Kennedy was shot in the head by Sirhan Sirhan at the Ambassador Hotel in Los Angeles. Beck said it was the first time the clothing had been on display.

Sandi Gibbons, a spokeswoman for the Los Angeles County district attorney's office, has viewed the clothing many times and said it contains spots that are likely blood.

Other items in the exhibit entitled "Behind the Scenes" included gloves and a knit cap from the O.J. Simpson murder trial and a rope tied around the neck of Sharon Tate and other weapons used when seven people were killed by the Manson family 40 years ago.

Debra Tate, the sister of Sharon Tate, said she and family members of other victims should have been notified in advance that evidence was going to be shown.

"A little warning would have been nice so we could prepare ourselves emotionally," Tate said. "It's part of the insensitivity the department shows toward victims. We're being victimized over and over again."

Tate plans to complain to the LAPD. However, she said she understands the value of the exhibit.

"I understand using it as a teaching tool and keeping the public aware of how heinous these murders were," she said. "From that aspect it's very important."

The Kennedy items were removed Tuesday before the exhibit opened to the public Wednesday.

The display was prepared by the Los Angeles Police Department for the 2010 California Homicide Investigators Conference at the Palms hotel and casino resort in Las Vegas. It also included photographs, video footage and vintage vehicles from Los Angeles homicide investigations spanning 100 years.

Palms owner George Maloof said he toured the exhibit and thought it was tastefully and professionally done.

Police spokesman Mary Grady said Kennedy family made the only complaint she was aware of. She said the evidence on display had all been presented in court and was part of the public record. Photos of many of the items were posted on Web sites, she said.

"We have a line of people out the door waiting to see it," Grady said.

Los Angeles District Attorney Steve Cooley said his office was pleased to contribute to the exhibit.

"The Los Angeles Police Department's homicide investigators have again and again demonstrated their ability to put together evidence on all sorts of crimes and certainly the more notorious killings in the city," he said.

Photographs and memorabilia from high-profile cases also were obtained from the Los Angeles Police Historical Society Museum. Other cases highlighted included Marilyn Monroe's death, the Black Dahlia murder, the 1997 North Hollywood bank shootout and the 1974 Symbionese Liberation Army shootout.