Annie Le's Person of Interest Had Scratches on Chest, Arms, Back

Raymond Clark, the lab technician who police have labeled a person of interest in the murder of Yale grad student Annie Le, has wounds on his chest, arms and back, sources told ABC News.

The deep scratches came to light as the Connecticut medical examiner released Le's cause of death as strangulation, or as it was officially described, "traumatic asphyxia due to neck compression."

Sources also said investigators are finding evidence that the pint-size scientist who weighed only 90 pounds put up a fierce struggle against her attacker.

Blood spatter was found on a laundry cart, and a bead from her necklace was found on the floor of the basement lab where she was killed and stuffed into a wall panel.

VIDEO: Police Search Home of Person of Interest in Yale Students MurderPlay

Police also found a pair of bloody surgical gloves.

ABC News has also learned that Clark sent a text message to Le early Tuesday, Sept. 8, requesting a meeting to discuss the cleanliness of the the cages of the mice in the research lab.

Le, a 24-year-old Ph.D. candidate, used the mice in her research. Clark, also 24-years-old, is not a student at the university and had more of a custodial role in the lab.

Police were able to track Clark's movements by reviewing the data from his digital key card, which shows he entered the building no fewer than 10 times, including after hours, on the day Le went missing, according to law enforcement sources.

VIDEO: Police focus on a lab technician in Annie Les death investigation.Play

The medical examiner's report came just hours after police took DNA samples from Clark and searched his apartment looking for clues.

Clark was released this morning. Police have not issued a warrant for his arrest.

Clark was taken into custody by police about 10:30 p.m. Tuesday on a warrant that allowed detectives to take DNA samples. Clark cooperated and was released around 3 a.m. today, said New Haven Police Department spokesman Joe Avery.

Police confirmed Wednesday that an additional warrant to search Clark's Ford Mustang was also served.

"He's not under arrest. We can't hold him," Avery said. "He was only made to comply with the warrant."

VIDEO: Police find body in university building where Annie Le was last seen.Play

Law enforcement sources said Clark failed a polygraph test when he was first brought in for questioning.

At a press conference Wednesday evening New Haven Police Chief James Lewis said Clark has retained an attorney and therefore could not be questioned further.

Lewis refused to comment on whether there was a relationship between Clark and Le beyond working together in the same building. He would not speculate as to a potential motive.

The chief would not confirm whether Le had been sexually assaulted.

Clark is being monitored by the police. Authorities continue to question other people in the building, but they have not served search warrants against anyone else.

"We're still in the process. We don't want to be accused of tunnel vision. We're still making sure who was in that building," said Lewis.

Lewis said Clark was handcuffed during the execution of the warrants because investigators were gathering DNA evidence from saliva, hair and fingernails and did not want anything tampering the process.

"We took him into custody to gather evidence from his body and his person," Lewis said.

Police said they have so far gathered 250 pieces of evidence.

Lewis said the arrest hinges now on the physical evidence and securing a DNA match.

"One match of a person at that location, we'd be going for an arrest warrant," he said.

On Wednesday, attorney David Dworski confirmed he was representing Clark.

"[Neither] my client nor I will be making any comments. We are working and cooperating with authoritiies on this investigation," Dworski told ABC News.

Investigators tailed Clark for several days, officials said.

Police said Clark had no criminal record but his name was mentioned in a police report from Branford, Conn., in 2003, reportedly connected to an alleged sexual assault.

Clark's sister, brother-in-law and fiancee, Jennifer Hromadka, also worked in the lab building but did not go to work today.

In a blog entry last year Hromadka denied rumors that Clark was having "a fling" with a woman at work.

"He is a bit naive, doesn't always use the best judgment, definitely is not the best judge of character, but he is a good guy," Hromadka, 23, blogged.

"My boyfriend Ray, if you don't know him, has no interest in any of the other girls at [the Yale lab] as anything more than friends," she wrote.

Police cars were parked all day outside Clark's apartment complex in Middletown, Conn., about 20 miles from Yale. Neighbors said surveillance cars have been at the complex for at least 24 hours.

One of Clark's neighbors, Felicia Diaz, told ABC News she saw Clark and his fiancee leaving their apartment in a hurry the same day Annie Le's body was discovered.

"I thought it was kind of suspicious where I thought he was moving out or something because it was a lot of luggage," Diaz said. "So I really didn't know what was going on."

Clark's landlord told ABC News that she wants Clark out of the apartment complex and has served an eviction notice to his lawyer.

ABC News consultant and former FBI agent Brad Garrett said that though he had been investigated by authorities for days, it's likely police did not take Clark into custody sooner because he was not a threat to other students.

"If you do not believe they are a danger to anyone else, then you may let him go," Garrett said. "If this is a crime of passion, you're not concerned about anyone else."

Sources have previously described a suspect as being a lab technician who worked in the same building where Le studied.

Le had been seen entering the Amistad Street lab around 10 a.m. Tuesday, but none of the cameras caught her leaving. Her body was found shortly after 5 p.m. Sunday, shoved into a space in the wall meant to conceal pipes and wiring.

The medical examiner did an abrupt about face Tuesday and withheld Le's autopsy results, which would have revealed the woman's exact cause of death. The medical examiner's office said it was being withheld at the request of the New Haven state's attorney.

"One of the reasons you do not release autopsy reports is you, as the medical examiner, want to have as much information as you can before you make that report," Garrett said. "[Clark] may make statements to police, or they may find evidence that would adjust the final report."

Annie Le's Death Shakes Yale University

A medical examiner positively identified the body found stuffed in a wall in a Yale University lab as the missing grad student Monday.

The body was found Sunday, the same day that the 24-year-old Le was supposed to get married.

Sources also told ABC News that bloody clothing, found behind ceiling tiles in the lab, contained evidence that linked the killer to the crime.

Investigators have been looking at Yale maintenance workers, people who worked in the lab and fellow students. Police tried to reassure Yale students that no other students are involved and no one else is in danger.

The building where the body was found is known for good security and not allowing people inside who don't have the proper Yale employee or student identification.

University President Richard Levin told students at a meeting Monday that they did not have to worry about a murderer being loose on campus, according to the Yale Daily News. He said the building's security system logged in anyone who visits the building and what time they enter and leave. That has allowed police to reduce the number of suspects to a handful of people, the paper reported.

Levin said the appropriate people were being monitored.

"The people in the basement aren't going to cause any trouble until the matter is resolved," he reportedly told the students.

Avery told today that authorities didn't start focusing on the lab until a few days after Le was reported missing. Police were initially unsure, he said, if she had disappeared voluntarily before her wedding, or if she had been a crime victim.

Video Surveillance Aids Search

Once video surveillance cameras revealed Le coming into the building Tuesday but not leaving, search efforts zeroed in on the building. Her body was eventually found, Avery said, by members of the Connecticut State Police Major Crimes Unit.

Friends and family had insisted for days that Le was not the kind of person to run out on her fiance, and the news that police had found a body was devastating. Le was to be married Sunday.

Wedding gifts had been left outside the family home of Le's fiance, Jonathan Widawsky. Their impending nuptials had led some to believe that Le had gotten cold feet and fled.

The discovery of the body ended a massive search by state and federal authorities that had expanded to a Connecticut waste processing facility in Hartford, in addition to the Yale lab, in the hopes of finding clues to her mysterious disappearance.

Using cadaver-sniffing dogs in round-the-clock shifts, FBI agents and state troopers dressed in hazardous material suits began searching the facility in Hartford Saturday night.

Police scanned blueprints of the lab and brought in blood-sniffing dogs, paying particular attention to the building's basement.

Yale had also offered a $10,000 reward for information leading to Le's whereabouts.

A Prescient Article Written by Le

Adding to the intrigue surrounding the case was an article Le wrote for a campus magazine earlier this year about how to stay safe on the Ivy League campus.

The article, titled "Crime and Safety in New Haven," was published in February in the magazine produced by Yale's medical school and compares higher instances of robbery in New Haven to other cities with Ivy League universities.

"In short, New Haven is a city and all cities have their perils," Le wrote. "But with a little street smarts, one can avoid becoming yet another statistic."

Le, who is 4 feet 11 and weighs 90 pounds, had left many of her belongings in the lab when she disappeared.

"She left her pocketbook, her cell phone, everything in the lab," Le's co-worker Debbie Apuzzo said.

Le's Facebook page showed her posing in wedding dresses and smiling with Widawsky, a Columbia University graduate student in physics, whom she described as her best friend.

"He's an amazing kid, just a wonderful, wonderful boy, and he must be heartbroken," Widawsky's friend Linda Matychack said. "I just can't imagine."

Le's family issued a statement Tuesday through a family friend, the Rev. Dennis Smith, thanking the local and state police and FBI for their hard work and sensitivity. He also mentioned staff members and students of Yale University. "Our loss would have been immeasurably more difficult to cope with without your support."

ABC News' Emily Friedman contributed to this report.