A Yale lab technician charged with the murder of graduate student Annie Le did not enter a plea during his arraignment in a Connecticut court Thursday.
Raymond Clark III, 24, kept his head bowed during the three-minute appearance in the suffocation death of Le, also 24. He said, "Yes, your honor," when asked whether he understood his rights. The judge then set bail at $3 million and sent him to a holding cell.
Le's body was found stuffed behind the wall of a campus research building on Sunday — the day she was scheduled to get married.
"Annie Le had unlimited potential. It is important to note that this is not about urban crime, university crime, domestic crime but an issue of workplace violence, which is becoming a growing concern around the country," New Haven Police Chief James Lewis said.
A law enforcement official said Clark was being described as a "control freak" who viewed the lab as his territory.
The official said Thursday that investigators don't know why Clark might have killed Le, because he won't talk to police. The official spoke on condition of anonymity because the investigation is ongoing and many details remain sealed.
Clark appeared in court with two public defenders. One of the attorneys, Joseph Lopez, said they would be handling Clark's case, which had previously been handled by a different lawyer. Lopez said he was still reviewing the case and declined to comment.
Police matched DNA from Clark to evidence found at the crime scene on the Ivy League campus where the medical examiner said Le was suffocated.
Clark was previously named a "person of interest" in the case and Lewis said there was no romantic relationship between the two.
He was arrested at the the Super 8 hotel in Cromwell, about 25 miles north of the Ivy League campus, where he had been staying since he was released early Wednesday by police, who had served search warrants looking for evidence linking him to Le's death.
Lewis said there are no other suspects. Authorities would not comment and a possible motive, other than to call it workplace violence.
Police said charges will be filed against anyone whose DNA matches evidence found at the crime scene.
Authorities compared DNA taken from Clark's hair, fingernails and saliva with more than 250 pieces of evidence collected at the crime scene in New Haven, Conn., and from Clark's Middletown, Conn., apartment.
The president of Yale University said Thursday that Clark's employment history of gave no clue he was capable of such a crime.
Richard Levin sent a message to the Yale community Thursday shortly after Clark's arrest. He said Clark has been a lab technician since December 2004.
Levin says the university doesn't tolerate violence, and will be soliciting suggestions about possible security improvements.
He says Le's killing says more about the dark side of the human soul than it does about security measures.
Le's body was found stuffed into a wall of the lab building where she did research and to which Clark had access. Dr. Wayne Carver in a brief statement on Wednesday said an autopsy of Le determined that she was murdered by "traumatic asphyxia" due to neck compression.
Clark is a Yale staff member who did custodial work at the laboratory, such as cleaning mouse cages. He has three relatives — his fiance, his sister and brother-in-law — that do similar work at the Yale lab.
Clark and several other people have been under constant surveillance. The New Haven Police chief declined to say who those people were.
Two new search warrants were issued on Wednesday for a red Ford Mustang belonging to Clark and for other undisclosed items.
Clark was taken into police custody late Tuesday and released 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.
Clark 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.
Clark lives in an 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.
Lewis 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.
Clark has been transferred to a state prison in New Haven.
FOX News' Rick Leventhal and The Associated Press contributed to this report.