A Sacramento County sheriff's legend stepped out of retirement and into a courtroom Tuesday to help jurors sort through the early years of a murder mystery that has lingered nearly two decades beyond his departure from his beat.

Ray Biondi is 75 and 19 years removed from a job where he helped crack cases with colorful names such as "The Thrill Killer," "The Vampire Slayer" and "The I-5 Strangler." But one he never conquered was the subject of his Sacramento Superior Court appearance – the slash-and-bludgeon sex killings of UC Davis "sweethearts" John Riggins and Sabrina Gonsalves.

Biondi supervised the sheriff's investigation into the Dec. 20, 1980, double homicide when the bodies were discovered in a ravine on his turf two days after the students' disappearance from Davis.

Then, when the Sacramento probe went dormant and a young Davis police detective picked it up, Biondi lent a hand. He found the small-town cop an informant.

He helped put them on to a key figure in a theory of murder that Biondi, at first, also found intriguing.

Then he watched from afar as Davis police arrested four people in an investigation that culminated in embarrassment when Yolo County prosecutors were forced to drop charges.

Eleven years after Biondi retired, Sacramento prosecutors in 2004 filed murder charges on Richard Joseph Hirschfield. The special-circumstance case says Hirschfield, 63, committed multiple murders and killed during the course of a rape. He faces the death penalty.

At the outset of the investigation 32 years ago, Biondi already was working one of the highest profile cases of his career – the serial sex-slave slayings of Gerald Gallego, who was later convicted of them and who died of cancer on death row.

It came to Biondi's attention that Gallego had a career criminal half brother named David Hunt, out on the streets. He assigned a detective, the late Stan Reed, to find and question Hunt.

The interview "wasn't very productive," Biondi testified. Hunt "was vague about where he was" at the time of the Riggins and Gonsalves killings, probably because he was then in the midst of what Biondi called "a multistate crime spree." Hunt dropped from sight. Biondi said the next he heard of Hunt, he was in federal prison.

Enter informant Ray Gonzales. Biondi testified a city police detective who used Gonzales in fencing investigations offered him up as an informant. Biondi said Gonzales claimed he was an old friend of Hunt's and that he had knowledge that Hunt, former cellmate Richard Thompson and a couple of other co-conspirators killed the students.

Biondi said he was dubious.

"In my experience, I learned not to trust (informants)," he testified. "They had their own agendas and were very good at manipulating law enforcement officers … telling us what we want to hear."

Still, Biondi heard Gonzales out. When Davis Police Detective Fred Turner picked up the moribund case a few years later, he put the two of them together to take a run at Hunt's old cellmate, Thompson, who was then living in a Skid Row hotel in Los Angeles.

The idea, Biondi said, was "to have Ray Gonzales make contact with Richard Thompson, establish some type of rapport with him … and pump him for information."

Turner fixed Gonzales up with a tape recorder. But the product of their work, Biondi said, was "unintelligible."

"We didn't think it was anything to get real excited about," Biondi said.

With Hunt locked up on federal charges in Lompoc, Biondi said he was willing to try a couple of different angles. He testified he worked with Turner to have Gonzales try to scare a confession out of Hunt's wife, Sueellen, with a fabricated story that Thompson planned to kill her because he thought she turned on her husband.

When the wife didn't waver, Biondi said he tried to get Gonzales into Lompoc to talk to Hunt. Federal officials wouldn't allow it, the detective testified.

Biondi then snuck Gonzales into a Nevada prison to work Gallego for information, defense attorney Linda Parisi said in a hearing outside the presence of the jury Tuesday.

Judge Michael W. Sweet would not allow her to ask in trial about the prison conversation between the two because he has deemed all matters Gallego irrelevant to the Hirschfield case.

Gonzales' efforts to get information on the so-called "Hunt Group" went nowhere, Biondi testified. Then, "We decided we didn't need him anymore," he said.

Not Turner. As the 1980s came to an end, Biondi said he kept tabs on Turner while the Davis detective went hard after the Hunts, Thompson and a fourth defendant named Douglas Lanier.

"We thought he had lost his objectivity," Biondi testified.

When DNA results excluded anyone in the Hunt Group from being the depositors of semen stains found on a blanket in Riggins' van, the Yolo DA's office dismissed the case on the four.

Hirschfield's lawyers have since picked it up, hoping to exonerate their client by saying the Hunt Group did it.

Both Turner and Gonzales are expected to testify in the Hirschfield trial.

So are former Sacramento County crime lab officials.

In his testimony Tuesday, Biondi said the Sacramento criminalists "came up … negative" in their initial biological examinations of assorted items of evidence, including the blanket.

It wasn't until 1992 that the state Department of Justice detected the DNA that Sacramento prosecutors say returned a match to Hirschfield's genetic material.

"We didn't know at the time we had any DNA evidence," Biondi testified, about the early days of the probe.

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