Twenty-three years after the fact, a now-retired Suffolk detective recalled trudging through brush south of the Long Island Expressway in Shirley to find a dead young woman.

Former Det. William Rathjen testified Thursday in Riverhead at the trial of John Bittrolff, 50, a Manorville carpenter. He is charged with second-degree murder in the killings of Rita Tangredi, 31, of East Patchogue on Nov. 2, 1993, and Colleen McNamee, 20, of Holbrook on Jan. 30, 1994.

Rathjen narrated a crime scene video taken the day McNamee’s body was found. He described walking through brush south of the eastbound on-ramp at Exit 68, passing construction and other debris, until a blue winter jacket was visible. A bit farther along, there was a pair of socks, one sneaker, some stretch pants and a pair of black jeans. Police searched the area after getting an anonymous call about the body.

And then there was McNamee’s body, posed similarly to the way Tangredi’s body was found almost three months before — naked on her back, legs spread with one arm over her head. Like Tangredi, her skull had been crushed.

During questioning by Assistant District Attorney Robert Biancavilla, Rathjen said he later identified the body as McNamee’s from her fingerprints. Police had her prints on file from a prostitution arrest.

Biancavilla has argued that Bittrolff is the killer because DNA from his semen was found on both bodies. He also said the similar poses and wood chips found on both bodies are significant, because of Bittrolff’s work as a carpenter.

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But as with Tangredi’s body, no wood chips were visible in crime scene photos of McNamee’s body.

“I cannot say that I saw wood chips,” Rathjen said during cross-examination by defense attorney William Keahon of Hauppauge. He also said he saw no blood on the ground. Parts of the ground near Tangredi’s body were soaked in blood.

Rathjen, during questioning by Biancavilla, said it was the Suffolk Crime Laboratory’s job, not his, to look for and collect evidence like wood chips.

In the years since the killings, the Suffolk Police Department destroyed the wood chips collected from both crime scenes, without ever photographing them. The department also destroyed wood shavings collected from the police car used by then-Sgt. Michael Murphy — since promoted to lieutenant — who was a suspect in the killings in 1998.

Keahon suggested in his opening statement that police did that to protect Murphy, who was the son of Thomas Murphy, the department’s chief of detectives at the time.

Keahon said his client’s DNA on both bodies is not evidence that he killed them.

Bittrolff, who was charged in 2014, faces a maximum of 50 years to life in prison if convicted.