The trash collector charged with the 2002 slaying of fashion writer Christa Worthington (search ) did not have a social relationship with her, the district attorney said.

Speaking at a press conference on Friday, Cape and Islands District Attorney Michael O'Keefe described the murder as a "crime of opportunity."

Christopher M. McCowen (search), who collected trash from Worthington's home on his route, was arraigned on Friday in Orleans District Court on charges of first degree murder, aggravated rape and armed assault. He pleaded innocent to all three charges and was ordered held without bail.

Worthington was found clothed only from the waist up, and there was evidence she had sex before she was killed. Media reports hinting that she was promiscuous led to further speculation a lover was involved. The charges were the first solid indication investigators believe she was raped.

"He knew Christa only in the sense that he was familiar with her comings and goings," O'Keefe said of McCowen. "They were not personal acquaintances, they were not friends in any way."

McCowen, 33, voluntarily submitted a DNA sample on March 18, 2004. The sample was not tested until April 7 of this year. After a match to DNA found at the crime scene was made, the sample was submitted for further testing and McCowen was located and monitored this week.

O'Keefe blamed a backlog in the medical examiner's office and forensics laboratories for the year-long gap.

"We have never doubted the science that our lab puts out. It is excellent. But we have a capacity problem and we need to continue to fix it," he said.

"We're not the only DA's office in the state that has serious cases," he added. "The state lab is operating with one hand tied behind its back."

O'Keefe would not specify how the DNA evidence was obtained or offer details on the murder, but said there was plenty of evidence not including the DNA to convict McCowen.

McCowen's court-appointed lawyer, Francis O'Boy, described the defendant's mood as "somber." Worthington's family was expected to make a statement later in the day.

Worthington, 46, wrote for Women's Wear Daily and Elle in New York and Paris. In 1997 she moved to Truro (search), where her family had spent summers, and became a single mother.

"She decided to come home to Truro for a safe and quiet life," Maria Flook, a local novelist who wrote a book about the murder, told FOX News.

On Jan. 6, 2002, Worthington's body was found stabbed to death on the kitchen floor, with her 2-year-old daughter clinging to her side. Police said Worthington may have been dead for more than 36 hours.

Investigators took some heat when in January, after the three-year anniversary of the murder passed, they requested DNA samples from all the men in Truro. Critics accused them of implying that residents who did not volunteer might come under closer scrutiny.

Several ex-boyfriends were closely looked at early in the investigation, including Tim Arnold, who found her body, and Tony Jackett, Provincetown's shellfish constable who fathered her child.

Police never named suspects, nor did they clear anyone of the crime.

"I'm kind of happy for Tim," Jackett told the Cape Cod Times on Thursday night. "I'm very guilty for pointing the finger at him. Of course, he did the same thing with me."

Worthington's daughter, Ava, lives in a Boston suburb and is being raised by friends of her mother, as stipulated in her will.

The Associated Press contributed to this report.