A retired police chief testified Wednesday that he unsuccessfully sought an arrest warrant for the older brother of Kennedy cousin Michael Skakel in the 1975 murder of a 15-year-old girl.

Thomas Keegan said during cross-examination by the defense that he presented an affidavit in 1976 to prosecutors seeking the arrest of Thomas Skakel. Keegan, then a Greenwich police captain and a lead investigator in the case, said prosecutors told him there was not enough evidence to establish probable cause.

The testimony was allowed over the objections of prosecutor Jonathan Benedict, who downplayed the warrant request. He said it simply indicated that at some point at least one police officer thought there was evidence against Thomas Skakel, who was the last person seen with Martha Moxley.

Now 41, Michael Skakel was indicted in January 2000 in Moxley's death. Her body was discovered beneath a tree on the family's Greenwich property on Oct. 30, 1975. She had been beaten with a golf club that investigators matched to a set in the Skakel household.

Michael Skakel was also 15 at the time; Thomas Skakel was 17. The brothers are nephews of Robert F. Kennedy's widow, Ethel.

Later Wednesday, forensics expert Dr. Henry Lee testified that there was no direct evidence to link Michael Skakel to the killing.

"We did not find any other person's blood type. We did not find any foreign DNA," Lee said.

There are no eyewitnesses to the killing and limited forensic evidence. During jury selection, prosecutors had asked jurors if they could understand the reasoning behind circumstantial evidence and put together a puzzle that might be missing a few pieces.

Thomas Skakel was an early focus of the investigation, along with Kenneth Littleton, a tutor at the Skakel home. Authorities are basing the case against Michael Skakel on admissions he allegedly made years after the murder.

Defense attorney Michael Sherman asked Keegan if he believed there was enough evidence to charge Thomas Skakel with the crime.

"You wouldn't just sign [the warrant] willy-nilly?" Sherman asked.

"It would not be a frivolous thing," Keegan responded.

Keegan said he never applied for an arrest warrant for Littleton and had no idea what has happened in the investigation since he retired in 1986.

Also Wednesday, jurors passed around a shoe that Moxley was wearing the night of her death. The word "Tom" was written on the shoe.

"That name was present when the shoe was taken from the victim," Keegan testified.