BARNSTABLE, Mass. — Prosecutors rested their case Wednesday against a garbage collector accused of murdering fashion writer Christa Worthington by reminding jurors of their strongest evidence — the defendant's own admissions that he had sex with the victim on the floor where she was found half-naked and dead.

Massachusetts State Police Sgt. William Burke told jurors about the constantly changing stories offered by defendant Christopher McCowen, 34, after he learned last year that his DNA matched genetic material from semen found on Worthington's body.

According to Burke, McCowen abandoned his claim that he barely knew the 46-year-old woman and instead told police that an acquaintance plunged a knife into her chest after McCowen had sex with her.

Before Assistant District Attorney Robert Welsh III rested the state's case Wednesday, defense attorney Robert George cross-examined Burke and suggested police mishandled one of Cape Cod's most sensational murders.

Specifically, George asked Burke whether he was aware that Truro Police Sgt. David Costa apparently was conducting his own investigation outside the supervision of the detectives formally assigned to the case.

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Costa, one of the first officers to arrive at Worthington's beach house after her body was discovered on Jan. 6, 2002, was seen using a metal detector on the grounds days later, George said. Some time later, George continued, Costa removed items from a mini-storage unit Worthington rented.

"No, I wasn't aware of that," Burke said.

Burke later testified that because Costa was not under his command, Costa was not required to seek permission from Burke to investigate leads.

Jurors are unaware of it, but earlier this year the defense failed to compel Costa and eight other people to submit blood, hair and fingerprint samples for analysis.

"These persons are likely to have had sexual or other connections to the alleged victim," George wrote in the motion, according to a published report. "It is undisputed that each of these parties has a direct connection to the victim."

The defense opened its case Wednesday by calling Keith Amato, another one of the eight people named in the motion. Amato formerly was married to the daughter of Anthony Jackett, a married man who fathered Worthington's daughter, Ava.

Amato, a sometimes movie extra and chef who now lives in New York, testified at length about heavy-handed tactics police used on him after concluding that he was lying about the state of his marriage and the reasons for a failed suicide attempt.

During a three-hour interview at the Truro Police Station, Amato recalled, troopers asked him about reports that he often showered at Worthington's house and was seen kissing her in public.

Amato insisted that he showered there once after coming off the beach, but denied having a relationship with Worthington. The suicide attempt was a "cry for help," Amato testified, but conceded that the intense pressure placed on him and Jackett's family after the murder contributed to his stress and emotional problems.

Amato told jurors that one trooper, Christopher Mason, looked him in the eye and said police knew about the suicide attempt.

"He said, 'Don't you think it looks pretty suspicious you [attempted] suicide? It shows maybe you had something to do with the murder,'" Amato testified.

When Burke relieved the two troopers who had been "badgering" him, Amato said he thought he was being "rescued" by the more senior investigator. Instead, Burke offered him a plea bargain.

"'This is the time in the interview where you get 25 to life, instead of life in prison,'" Burke said, according to Amato.

"I felt like throwing up. I couldn't even respond," Amato told jurors. "Then I said, 'You are not going to pin this murder on me. This is the end of the interview. Have a nice day.'"

The defense claims police were jumping from suspect to suspect until they found one — McCowen — who lacked the intellect and resources to stand up to overzealous homicide detectives.

Model employee

Another defense witness, McCowen's boss at Cape Cod Disposal, told jurors that the defendant was generally a good worker, despite having tested positive once for marijuana use.

McCowen usually showed up at time, was able to find the addresses on his route, and never was the subject of complaints from customers, said the witness, Donald Horton. The only feedback the company received about McCowen was good, he said.

"It was positive. They like him. In fact, they still ask about him," Horton said. "Elderly ladies would bake him cookies. They loved him. They just loved him."

On cross-examination, Horton rebuffed suggestions by the prosecutor that his opinion of McCowen now may be influenced by the fact that Worthington's family filed a $10 million lawsuit naming Cape Cod Disposal weeks after McCowen's arrest last year.

The defense case is expected to continue into early next week.

Testimony will be suspended for at least a half day to facilitate a jury view of Worthington's former beach house. Judge Gary Nickerson told an attorney representing the trust that now owns the North Truro home that the public and media will be barred from attending.

If convicted of first-degree murder and aggravated rape, McCowen faces life in prison without parole. The trial is being shown live at Court TV Extra.