On the last day of testimony in the double-murder trial of a Manorville carpenter, the defense established Thursday that other men were said to have threatened the victims — and even admitted to killing one of them — but police discounted them as suspects based on DNA evidence.

Instead, retired Suffolk homicide Det. John McLeer told defense attorney William Keahon of Happauge that the deaths of Rita Tangredi, 31, of East Patchogue, and Colleen McNamee, 20, of Holbrook, remained unsolved for almost 20 years until the DNA from their bodies was found to match that of the defendant, John Bittrolff.

Bittrolff, 50, is charged with second-degree murder in the deaths of Tangredi on Nov. 2, 1993, and McNamee, whose body was found Jan. 30, 1994. Both women, who worked as prostitutes, were strangled and bludgeoned to death and posed similarly.

Except for Bittrolff’s DNA, there has been no evidence or testimony presented during seven weeks of testimony that directly links him to the victims or crime scenes. Keahon has argued that his client’s DNA — found in his semen — is not evidence of murder.

“Anyone in this case, no matter what they did in this case to become suspects, once their DNA didn’t match, the investigation ended, is that right?” Keahon asked McLeer in the Riverhead courtroom.

McLeer said that was true.

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Others investigated included:

  • Former Suffolk police Officer Teddy Hart. McLeer acknowledged that Hart was fired in 2001 and pleaded guilty to aggravated harassment for calling women and threatening to rape and mutilate them. Hart also kept missing persons reports in his home and patronized prostitutes, McLeer said.
  • Tangredi’s estranged husband, Frank Beinlich. Witnesses told police he admitted killing her, and accurately described how and where she was killed. McLeer said Beinlich told police that Tangredi — who once accused Beinlich of rape — had caused him a “lot of heartache” and that when he saw her the day before she died, she threw a beer bottle at his car.
  • A then-18-year-old man who reportedly told others he’d killed Tangredi. McLeer said this man lived within walking distance of where her body was found.
  • The boyfriend of the 18-year-old’s mother, who was with Tangredi two nights before she was killed. Keahon suggested this man tried to have sex with Tangredi then but she refused because he had no money.

Keahon also questioned the witness about former Sgt. Michael Murphy — since promoted to lieutenant — who was investigated because numerous prostitutes had accused him of forcing them to give him sex for free.

“Did you learn that Sgt. Murphy had impregnated a 15-year-old prostitute? And that he forced her to leave the county?” Keahon asked. State Supreme Court Justice Richard Ambro sustained objections to those questions, so McLeer did not answer.

Suffolk police declined to comment on Murphy or to make him available.

Closing arguments will be Monday.