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MIDDLETOWN, Conn. (CBS News) ― Police and FBI agents staged a dramatic raid on the home of a Yale University animal research technician on Tuesday, seeking evidence that might tie him to the slaying of a graduate student whose body was found stuffed behind a wall in a campus research building.

No charges were filed against 24-year-old Raymond Clark III in Middletown, but police took him into custody while searching for DNA and other physical evidence. Police said Clark would be released after they obtain evidence they need from him and his Middletown apartment.

Clark was handcuffed and escorted out of the apartment building in Middletown and into a silver car. Neighbors leaned over the apartment building's iron railings and cheered as police led him away. CBS affiliate WFSB reported that 18 FBI agents went into the apartment just after 10 p.m.

New Haven Police Chief James Lewis described Clark as a person of interest, not a suspect, in the death of 24-year-old Annie Le, whose body was found Sunday, the day she was to be married. He said police were hoping to compare DNA taken from Clark's hair, fingernails and saliva to more than 150 pieces of evidence collected from the crime scene. That evidence may also be compared at a state lab with DNA samples given voluntarily from other people with access to the crime scene.

"We're going to narrow this down," Lewis said. "We're going to do this as quickly as we can."

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

Investigators began staking out Clark's home on Monday, a day after they discovered Le's body hidden in the basement of a research building at Yale's medical school. She vanished Sept. 8.

Clark shares the apartment with his girlfriend, Jennifer Hromadka, whom he is engaged to marry in December 2011, according to the couple's wedding Web site.

Middletown is about 20 miles north of New Haven.

Neither the couple nor Clark's parents returned repeated telephone calls Tuesday.

Clark moved to Middletown from New Haven six months ago, where he shared an apartment with his girlfriend and three cats, according to former neighbor Taylor Goodwin, 16.

"I never really talked to him much," Goodwin said. "He was just some guy."

Police have said Clark is a lab technician at Yale. It's unclear how long he worked there and Clark's supervisors would not comment Tuesday.

Le worked for a Yale laboratory that conducted experiments on mice, and investigators found her body stuffed in the basement wall of a facility that housed research animals. Clark works in the lab as a technician.

Authorities had been tightlipped since Le was reported missing, just a few days before her wedding day. Police say they have ruled out her fiancee, a Columbia University graduate student, as a suspect but have provided little additional information.

Law enforcement sources tell CBS News correspondent Randall Pinkston that when Clark was first questioned, investigators noticed marks and scratches on his body, most notably on his hands and arms - suggestive of defensive wounds.

Officials had promised Tuesday to release an autopsy report that would shed light on exactly how Le died. But then prosecutors blocked release of the results out of concern that it could hinder the investigation.

Investigators usually have reasons for keeping information secret during a criminal probe, said David Zlotnick, a former federal prosecutor who now teaches law at Roger Williams University in Bristol, R.I.

Secrecy helps police confront possible suspects with little-known evidence about a crime and makes it harder them to fabricate a cover story.

"Having that information secret or private helps the investigators know, first of all, what buttons to push on the person, and it makes sure they haven't tainted the investigation," Zlotnick said.

Le's body was found Sunday, the day she would have been married on New York's Long Island. Her remains had been crammed into a wall recess where utilities and cables run between floors.

The Le family issued a statement Tuesday through a family friend, the Rev. Dennis Smith, that thanked friends and the Yale community for their support during their grieving. The family also asked for privacy.

"The entire Yale community as well as our extended families and friends have been very supportive, helpful and caring," said Smith, speaking for the family. "Our loss would have been immeasurably more difficult to cope with without their support."

The secrecy surrounding the case has bred confusion in some quarters, and officials have repeatedly denied media reports.

"You guys made up the fact that we had somebody in custody, the media in general," New Haven police spokesman Joe Avery told reporters outside the police department Tuesday.

The lack of information also has led to some measure of fear at Yale, which last dealt with a homicide in 1998 - the sensational and still-unsolved stabbing death of 21-year-old Suzanne Jovin about 2 miles from campus.

Yale President Richard Levin was more forthcoming to Yale medical students, telling them Monday that police have narrowed the number of potential suspects to a small pool because building security systems recorded who entered the building and what times they entered.

Several news organizations have reported that police were interviewing a possible suspect who failed a polygraph test and had defensive wounds on his body. At least one reported Tuesday that it was the lab technician in Middletown.

Along the way, various media have reported that Le was stabbed, that police found her bloody clothes and that a professor was a prime suspect - virtually all claims unconfirmed by police or met by flat denials.

New Haven police said they would restrict information even more in coming days after an NBC producer was injured Tuesday as reporters outside the police department pushed to surround a spokesman during a briefing.

The building where Le's body is accessible to Yale personnel with identification cards. Some 75 video surveillance cameras monitor all doorways.

Her body was found in the basement, which houses rodents, mostly mice, used for scientific testing by multiple Yale researchers, Alpern said.

"That this horrible tragedy happened at all is incomprehensible," said Le's roommate, Natalie Powers. "That it happened to her, I think is infinitely more so. It seems completely senseless."

(© 2010 CBS Broadcasting Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)