BUFFALO - Spit secretly swabbed from a sidewalk was the key to cracking one of the city's oldest unsolved murders, the 1974 rape and stabbing of a young mother, a prosecutor told jurors Monday as the suspect's trial began.

Leon Chatt, 61, was charged in February with the murder of Barbara Lloyd after police cold case investigators said they matched DNA extracted from his recently collected saliva to crime scene evidence collected three decades earlier.

“Thirty-three years after the death of Barbara Lloyd, science has given us justice,” Assistant District Attorney Letizia Tagliafierro said in state Supreme Court.

Lloyd's two, now-grown children said outside the courtroom they were “relieved” to see Chatt, their mother's brother-in-law, on trial.

Joseph Lloyd was 3 and Kimberly Lloyd was 18 months old when their 27-year-old mother was raped and stabbed at least 16 times with one of her kitchen knives as they slept nearby in their Buffalo home.

Their father was out at the time.

In 2003, the brother and sister asked the police cold case squad to take another look at their mother's case, and Chatt, who they had suspected through the years.

Chatt, known as “Rusty,” has pleaded not guilty to a charge of second-degree murder. Wearing a black, button-down shirt and tan pants, he sat with his arms crossed at the defense table, occasionally raising his eyebrows as Tagliafierro described how police zeroed in on him.

“Police followed Rusty, went through his trash, until one day in 2006, when this defendant spat on the ground when he was wiping the snow off his windshield,” Tagliafierro said.

An investigator waited for Chatt to leave and then picked up the saliva with a cotton swab, she said.

It was matched to DNA taken from pubic hairs found on Lloyd at the murder scene and preserved in an evidence room for more than 30 years.

Defense attorney John Jordan called “preposterous” the prosecutor's claim that the DNA evidence was “unassailable” proof of Chatt's guilt.

“That was a nice story by Miss Tagliafierro, but that's all it was, a story,” Jordan told jurors during his opening statement. He urged them to listen closely to each witness to assess their credibility and said there was no “direct evidence” to link Chatt to the crime.

“Please keep an open mind,” the defense lawyer said.

Barbara Lloyd's body, the knife protruding from her chest, was found by her husband, Galan Lloyd, in their bedroom after he returned from a night out with friends that included some time with Chatt, who had met up with him at a bar sometime after the killing.

Galan Lloyd was interrogated at length before being ruled out as a suspect.

The trial's first witness, William Leggett, said he and Chatt were “drinking buddies” in the 1970s.

He testified that Chatt seemed infatuated with Lloyd and had remarked several times the day of the killing that he wanted to have sex with her.

Chatt was married to Barbara Lloyd's stepsister at the time.

Chatt and his wife eventually moved to Georgia and Arizona and divorced. Chatt spent time in prison on a 1984 forgery conviction and again on a 1994 burglary conviction before returning to Buffalo.