New Haven police say it may be hours until they receive DNA results from items seized from a Yale research technician, in relation to the murder of graduate student at the university.

Chief James Lewis said at a press conference held early Wednesday evening that police were awaiting results from DNA that taken from animal research technician Raymond Clark III. the results are expected to show if it connects hom to more than 250 pieces of evidence collected from the crime scene.

Lewis described Clark, 23, as a Yale staff member who did custodial work at the laboratory, such as cleaning mouse cages. He said that he has three relatives — his fiance, his sister and brother-in-law — that do similar work at the Yale lab.

Lewis did answer questions on the relationships between Clark, his family members and graduate student Annie Le.

"[Clark] is the only person we currently have a search warrant for at this time," said Lewis.

Lewis says Clark and several other people are under constant surveillance. He declined to say who those people were were.

He said charges will be filed against anyone whose DNA matches evidence found at the crime scene.

Police also said two new search warrant were issued for a Ford Mustang belonging to Clark and for other undisclosed items.

Dr. Wayne Carver in a brief statement said an autopsy of Le, 24, determined that she was murdered by "traumatic asphyxia" due to neck compression. There were no other details immediately available.

Clark was released from police custody Wednesday at 3 a.m. after authorities collected DNA samples from him, questioned him and searched his apartment. No charges have been filed against him.

He said through his lawyer that he wanted to cooperate with the investigation. His attorney David Dworski said Wednesday his client is "committed to proceeding appropriately with the authorities." He would not comment further.

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Clark was taken into police custody in handcuffs Tuesday night while officers and FBI agents searched the Middletown, Conn., apartment he shares with his fiancee for DNA and other physical evidence that might tie him to Le's killing.

Le disappeared suddenly on Sept. 8, less than a week before she was to be married. Her body was discovered Sunday — the day her wedding had been planned for — hidden behind a wall in a Yale lab building where Clark worked and she did research for her doctoral program in pharmacology.

Clark lives in his apartment with fiancee Jennifer Hromadka, whom he plans to marry in December 2011, according to the couple's wedding Web site.

Among the possible motives detectives are mulling over is Clark's reported criticism of Le for her handling of the lab mice the two worked with, according to the New York Daily News.

Citing e-mails the pair reportedly exchanged, the Daily News said Clark had accused Le of failing to follow protocol when handling the mice, and she'd promised to do better.

Late Tuesday, capping a weeklong hunt first for Le and then for her killer, Clark was escorted out of his apartment and into a silver car. Neighbors leaned over the building's iron railings and cheered as police led him away.

New Haven Police Chief James Lewis described Clark as a person of interest, not a suspect, in the death of Le.

Lewis wouldn't confirm that Clark had scratches on his body and had failed an FBI-administered lie detector test, but denied rumors that Clark had been on the run.

"We've known where he was all along," Lewis told reporters.

The chief also declined to comment on reports that Clark's fiancee had contacted authorities Tuesday night when he came home with scratches, wearing different clothes than the ones he'd left for work in.

Hromadka wrote on her MySpace page that she's not perfect, but cautioned people not to judge her.

"Who are you to judge the life I live? I know I'm not perfect and I don't live to be, but before you start pointing fingers make sure your hands are clean!!" the 23-year-old wrote.

The date of the MySpace posting is unclear. The page has since been taken down.

Overnight, state police officers sorted through items on a card table set up outside Clark's ground-floor apartment's door. A tow truck took away a red Ford Mustang neighbors say was used by Clark.

A resident of the complex, Rick Tarallo said he, his wife and 6-month-old daughter live in a unit next to Clark and his fiancee, Jennifer Hromadka.

He said the couple was "really quiet" and lived with an older man, whom he speculated was one of their fathers.

"He seemed like a good guy," Tarallo said of Clark. "They didn't strike me as someone who would try to kill somebody."

Police started tearing down the yellow crime scene tape as daylight broke. At that point there had been no sign of Clark's return to his apartment, and neighbors said they hadn't seen Hromadka in the area for days.

Loraine Falcon, 32, a nurse aid who lives in Clark's building, said the police activity kept her and her three kids — ages 15, 10 and 8 — up much of the night and left her fearful for their safety.

"I just want to know if he did it," Falcon said.

Clark's apartment appeared empty Wednesday morning after police left. No one answered the door.

During the search, one officer commented that the apartment smelled like animals. Multiple neighbors said they saw Clark and Hromadka load luggage, cats and two rodents into a vehicle on Saturday.

Falcon said she also saw Clark loading a suitcase and a duffel bag into a car Sunday at about 5 p.m.

Police have collected more than 700 hours of videotape and sifted through computer records documenting who entered what parts of the research building where Le was found dead.

In addition to Clark and Hromadka, Clark's sister and brother-in-law were also technicians at Yale's Animal Resources Center, according to Yale records.

On Tuesday, state prosecutors blocked the release of Le's autopsy results, reasoning that they could hinder their investigation. The Connecticut medical examiner had already called the death a homicide but hadn't reported the manner of Le's death.

FOX News' Rick Leventhal and The Associated Press contributed to this report.

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