The prosecution presented its strongest evidence Wednesday linking a Manorville carpenter to the bodies of two women strangled and bludgeoned to death more than 23 years ago.

Forensic scientist Robert Baumann of the Suffolk Crime Laboratory testified in Riverhead that DNA in semen recovered from the bodies of Rita Tangredi, 31, of East Patchogue, and Colleen McNamee, 20, of Holbrook, matched the DNA of the man accused of killing them, John Bittrolff, 50.

He is on trial in Riverhead, charged with second-degree murder, before state Supreme Court Justice Richard Ambro.

Since shortly after the women’s deaths, earlier, less sensitive forms of DNA testing suggested the semen from Tangredi’s killing on Nov. 2, 1993, and McNamee’s killing on Jan. 30, 1994, came from the same person.

During questioning Wednesday by Assistant District Attorney Robert Biancavilla, Baummann said that after Bittrolff’s arrest in July 2014, he retested the semen samples, compared it Bittrolff’s DNA and found a match.

Baumann said the likelihood that the DNA came from someone else unrelated to Bittrolff was 1 in 81.8 quintillion. That number is more than 750 million times the number of people who have ever lived.

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“That’s a pretty unique [DNA] profile, would you agree?” a smiling Biancavilla asked.

“The statistics seem to support that,” Baumann replied.

Baumann said he also tested DNA found in the fingernail clippings of Tangredi’s left hand. That included a partial profile that mostly matched Bittrolff’s profile, leaving a likelihood of 1 in 608 quadrillion that it come from another, unrelated man, he said.

Baumann said the ability to get DNA profiles so long after the killings reflects how well the lab preserved the evidence it collected then.

“I don’t test too much evidence that’s 23 years old,” he said. “So apparently they held up.”

As strong as the DNA evidence is, the defense has discounted its importance. Defense attorney William Keahon of Hauppauge argued in his opening statement that the DNA is not evidence of murder, and that there is nothing else that connects his client to the women, who worked as prostitutes.

The defense has suggested that numerous other men could have killed either or both women, noting that police over the years investigated 152 other suspects.

On Tuesday, Officer Linda Passarella testified that evidence collected from one of those suspects, Officer Teddy Hart, was destroyed by the department. She said the department’s Property Section, which warehouses old evidence, periodically clears out old items to make room for new evidence.

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In 2006, some of those old items were clothing, hairs and swabs collected during a “confidential” Internal Affairs investigation of Hart, who was fired in 2001 and pleaded guilty to aggravated harassment after an investigation showed he called women and threatened to rape and mutilate them.

Passarella said there was no indication on paperwork that the Hart evidence had anything to do with a homicide investigation.