Investigation Urged in LAPD’s Handling of Kennedy Slaying : Assassination: Former aide and retired law enforcement officials call for a grand jury probe, saying police deliberately suppressed evidence and coerced witnesses.

A group of former law enforcement officials, politicians and celebrities called Thursday for a grand jury investigation into alleged “willful and corrupt misconduct” by the Los Angeles Police Department in the handling of the investigation of Robert F. Kennedy’s assassination.

The group is led by Paul Schrade, a former Kennedy aide who was wounded in the kitchen of Los Angeles’ Ambassador Hotel June 5, 1968, when Kennedy was shot. Schrade has examined more than 50,000 pages of files on Kennedy’s assassination, most of which were released four years ago.

“We are not charging any grand interlocking conspiracy” to kill Kennedy, Schrade said at a news conference Thursday. But he alleged police misconduct, saying that the LAPD suppressed and destroyed evidence, manipulated and coerced witnesses and failed to pursue obvious leads. Because of the mishandling of the case, investigators may have reached wrong conclusions, Schrade said.

Police Chief Daryl F. Gates declined to respond to the allegations.

“This has been looked at a number of times before and it hasn’t resulted in anything different, so I am not going to comment,” Gates said.

Among those calling for the inquiry are Sam Dash, former counsel to the U.S. Senate Watergate Committee; John H. Gordon, a member of Mayor Tom Bradley’s advisory committee on the LAPD’s Kennedy assassination files; Robert F. Joling, former president of the American Academy of Forensic Sciences; Frank Mankiewicz, Kennedy’s former press secretary; Arthur Schlesinger Jr., former special adviser to President John F. Kennedy; Patricia Duff, former special assistant on the House Select Committee on Assassinations, movie director Oliver Stone and several other Hollywood personalities.

At the news conference, Schrade contended that 50,000 pages of LAPD files made public in 1988, plus files from the FBI and the Los Angeles County district attorney’s office show that the LAPD discounted and discredited witnesses’ reports of events immediately after the shooting and falsified or destroyed key evidence.

When the files were released by the state archives, state officials acknowledged that 2,400 photographs had been destroyed by the LAPD two months after the assassination.

Schrade contended Thursday that other evidence was also destroyed, including pieces of wall that allegedly contained bullets that may have come from a gun other than the one wielded by Sirhan Sirhan, who is serving a life sentence for the killing.

The LAPD concluded that Sirhan was the lone gunman in the case, a conclusion also reached by a special investigator hired by the Los Angeles County Board of Supervisors in 1975.

But William A. Bailey, a former FBI agent who was at the news conference and who worked on the assassination investigation, said he saw two bullet holes in a hotel kitchen wall that are not explained in the LAPD files.

Schrade said that among other evidence provided to the grand jury Thursday is a signed statement from retired LAPD Sgt. Paul Sharaga contending a report in the LAPD files purporting to describe an interview with him “contains false and deliberately misleading statements.”

The report “is obviously derived from a much longer report personally prepared by me . . . which disappeared from the LAPD files under entirely suspicious circumstances,” the statement said. Sharaga, who lives in another state, was not at the news conference and could not be reached for comment.

Schrade also played a tape of a polygraph examination of Sandra Serrano, who was at the hotel on the night of the assassination. Serrano told police she saw a couple rush from the hotel and heard the woman say: “We shot Kennedy.” John F. Burns, a state archivist confirmed Thursday in a telephone interview with The Times that he listened to the tape and wrote about it in a letter last month to Philip Melanson at Southeastern Massachusetts University, one of the people calling for the grand jury investigation.

Burns wrote in his letter that the polygraph examiner “clearly . . . wanted Sandra Serrano to recant her original story. His questioning of her was typical of his demeanor with other witnesses.”

This was the second time this week that a call has been made for a grand jury review of an LAPD investigation. On Tuesday, the Los Angeles City Council asked the grand jury to determine if the LAPD wrongfully helped convict two men who spent 17 years in prison for killing a sheriff’s deputy.