AUTHORITIES HAVE 'PERSON OF INTEREST' IN YALE KILLING Reporting was contributed by Simon Akam, Lynnley Browning, Russ Buettner, Alison Leigh Cowan, Robert Davey, Lisa W. Foderaro and Nate Schweber. The authorities in Connecticut identified a laboratory technician as 'person of interest' in the killing of Annie Le, a 24-year-old graduate student whose body was found behind a basement wall in a medical research building at Yale University, a law enforcement official said on Tuesday. Chief James Lewis of the New Haven police said the technician, Raymond Clark III, 24, was in custody but did not call him a suspect. Lewis said the police had a warrant to take samples of Clark's hair, saliva and fingernails for DNA testing. 'If he cooperates and gives us the evidence,' Lewis said at a news conference at police headquarters in New Haven on Tuesday night, 'he will be released.' He said Clark would either be arrested or exonerated by the end of this week. Lewis said investigators had taken about 150 items from the crime scene with potential DNA evidence they could compare. He also said they had interviewed 150 people and watched 700 hours of surveillance video from the cameras in and around the building where Le's body was found -- and where Clark also worked. Clark had been a focus for investigators at least since Monday, when unmarked police cars pulled up to the apartment complex in Middletown, Conn., where he lives. He was not there. Neighbors said that on Sunday afternoon, around the time Le's body was discovered, he left with his fiancee, who is also a technician at the Yale lab. The neighbors said they got into a Ford Taurus that drove away. It was not clear when he returned -- no one answered the door in midafternoon. But the police picked him up there around 10 p.m. on Tuesday, a week after Le disappeared and two days after she was to have been married on Long Island. Officials appeared to be moving cautiously with the investigation on Tuesday. For much of the day, they declined to say officially if anyone was considered a suspect. And when Lewis appeared at the news conference, he said that investigators were still looking at other people who had access to the building, near the Yale Medical School. 'We are making sure there are not any other suspects, making sure we don't have tunnel vision,' Lewis said. He declined to discuss how Le had died. The chief state medical examiner's office said it would release the cause of death on Tuesday afternoon. But it did not do so, saying the state's attorney in New Haven had asked that the information not be released 'in order to facilitate their investigation.' Some newspaper and television reports said the police were close to filing charges. But a New Haven police spokesman, Officer Joe Avery, repeatedly denied that an arrest was imminent. A researcher at another Yale lab in the building where Le's body was found said that Clark had not been at work for several days. Besides his companion, his sister and brother-in-law also work as animal research technicians at Yale. The researcher said Clark was 'very officious and very demanding' and had given graduate students who worked as investigators a hard time. 'For example, you're supposed to wear shoe covers on your feet, and he would make a big deal of it, instead of just requesting that they wear them,' said the researcher, who asked not to be identified. 'I told his supervisor.' Ann Marie Goodwin, a resident at a Victorian-style house in New Haven where Clark and his companion lived until about a year ago, described him as 'very unsociable.' On Tuesday night, a man who identified himself as Pastor Dennis Smith read a statement on behalf of the families of Le and her fiance, Jonathan Widawsky, whom Le met at Rochester and who is now a graduate student at Columbia University. Standing outside Woodbridge Hall on the Yale campus, Smith said the families wanted 'to thank everyone in the community and around the nation for the thoughts and prayers.' He cited a number of law enforcement agencies, including the New Haven Police Department and the FBI, for the 'professional and compassionate manner in which they are conducting the investigation.' 'Our loss would have been immensely more difficult without their support,' he said. After thanking the president of Yale, Richard C. Levin, he left, answering no questions. Le, who often worked with laboratory mice in the building where she was found, was part of a research team led by a faculty adviser, Anton Bennett. According to its Web site, his laboratory was doing enzyme research that could bear on cancer, diabetes and muscular dystrophy. Vanessa J. Flores, a medical student at the University of Pittsburgh, said she met Le in 2005 when they both applied for a scholarship program at the National Institutes of Health in Bethesda, Md. Both were accepted, and they spent time together that summer. They had kept in touch, and Flores had planned to attend Le's wedding. Flores said Le and Widawsky were introduced by a mutual friend. Both were shy about relationships, Flores said, and it took some time for a friendship to evolve into something romantic. Going to different graduate schools was a difficult decision, Flores said, but they had decided to make it work. 'That's why Jon was such a perfect fit for her,' Flores said. 'He would never make her feel like her career had to come second.' When a guest Le had invited to the wedding jokingly complained in an e-mail message to many of their friends that he would have to miss a New York Giants game to attend, Le responded that they were also going to miss the finals of the U.S. Open tennis tournament, the MTV Video Music Awards, a Mets doubleheader and a pet expo. 'It hurts me too,' Le wrote, according to Flores. 