Police investigating the killing of Yale graduate student Annie Le are still collecting evidence, including a Ford Taurus they towed from a motel overnight, but they say everything they have seen points to one suspect in the strangling -- 24-year-old Yale lab technician Ray Clark.
New Haven, Conn., Police Chief James Lewis told ABC New's New Haven affiliate WTNH-TV that investigators are not actively looking for any other suspects in the case at this time.
"There's no second arrest pending," Lewis told ABC.
Some have speculated that other suspects might be involved in the murder because Clark's fiancee, sister and brother-in-law all work at Yale, all at 10 Amistad St., where police say Le was killed.
Still, investigators still have not found a motive behind the killing of the young woman, whose body was found on Sept. 13 -- the day she had been supposed to get married.
"The only person who knows the motive is the suspect," Lewis said. "It's true in many cases. You never know absolutely unless the person confesses, and in this case it's too early to tell."
Friends and co-workers have called Clark a "control freak" who was territorial about the mice whose cages he cleaned. Investigators are looking at whether that attitude may have contributed to an argument between Le and Clark.
Clark was tailed by the city's narcotics police for several days before his arrest at a Motel 8 in Cromwell, Conn., on Sept. 17. The suspect was playing a softball game on the day that Le's body was found crammed in the Yale lab wall.
Police found DNA of both the Clark and Le in the ceiling and in the wall recess, an official told the Hartford Courant newspaper.
New Haven police would not tell ABCNews.com who owned the car towed from the motel, but a state trooper confirmed to The Associated Press that the seizure was related to Clark's arrest.
Clark's father, Raymond Clark III, had checked in to the motel before his son was arrested, but it was unclear whether he was still living there, according to the AP. He is divorced from the suspects mother, Diane Clark.
Clark, whose bond was set at $3 million and who did not enter a plea, is being held at a maximum security facility.
Sources told ABC News that Clark refused to be interviewed by authorities.
Investigators have gathered more than 250 pieces of evidence in the case, sources told ABC News, including text messages exchanged between Clark and Le arranging to meet on the day she disappeared.
Clark was taken into custody by police early Thursday after investigators stood vigil all night outside the Super 8 motel in Cromwell, where the suspect had retreated to room 214 on Wednesday. Earlier Wednesday, police had taken DNA samples from Clark, searched his apartment and then let him go.
A convoy of police and FBI cars pulled into the motel parking lot with lights flashing about 8:20 a.m., while others blocked off the intersection. FBI agents ran up stairs at the back of the motel. Clark was arrested minutes later without incident.
At a news conference held almost simultaneously with the arrest, Lewis said, "There were no issues with the arrest. It went smoothly."
Lewis has dismissed rumors of a romantic relationship between Clark and Le, and said Le's murder was part of a growing wave of workplace crime.
"This is not about urban crime, university crime, or campus crime. It's about workplace violence, a growing concern across the country," he said.
Yale University President Richard C. Levin released a statement that said in part, "Mr. Clark has been a lab technician at Yale since December 2004. His supervisor reports that nothing in the history of his employment at the university gave an indication that his involvement in such a crime might be possible."
He added, "This incident could have happened in any city, in any university, or in any workplace. It says more about the dark side of the human soul than it does about the extent of security measures."
Suspect's, Victim's Lab Movements Tracked by I.D. Cards
Clark has wounds on his chest, arms and back, sources told ABC News, suggesting a violent struggle. A bead from Le's necklace was found on the floor of the basement lab where Le's body and blood spots were found on a laundry cart there.
Sources told the Hartford Courant that Clark's Yale swipe card indicated he was the last person to see Le alive. The electronic trail left by his card indicated he had entered the same lab where Le was last seen. Clark also reportedly swiped his identification card at least 10 times in the hours surrounding Le's disappearance, the paper reported.
The deep scratches on Clark's body 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."
Police also found a pair of bloody surgical gloves.
ABC News has also learned that Clark sent a text message to Le at some point, requesting a meeting to discuss the cleanliness of the cages of the research mice.
Le, a 24-year-old Ph.D. candidate, used the mice for her research. Clark is not a student at the university and had more of a custodial role in the lab.
Police could 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.
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 this week.
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.
ABC News' Don Ennis and Brian Cohen contributed to this report