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 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.
Though police have seemingly narrowed in on a suspect, the mood around Yale is still one of sadness and uncertainty. The last on-campus murder was the 1998 stabbing death of 21-year-old Suzanne Jovin. There has been no arrest in her death.
Reached in Germany, Thomas Jovin told ABCNews.com that he did not wish to comment on Le's murder or his daughter's.
Hundreds of students and faculty members turned out Monday night for a candlelight vigil and prayer service at the Yale campus.
Avery told ABCNews.com 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.
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, he said, by members of the Connecticut State Police Major Crimes Unit.
Vanessa Flores, Le's former roommate, said she heard the news on the Internet about her friend's body likely being found.
"I had a very tough time just reading the headline," she told "Good Morning America" today. "It was very difficult."
Flores said she doesn't know why anyone would want to kill her friend, who earlier this year had written a piece for the University Magazine questioning the safety of the New Haven campus.
"The only thing I can possibly think of right now is maybe a psychopath, an anti-social person who, I don't know, maybe got upset about what she wrote back in February about not being safe," she said.
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.
But Flores said Widawsky was "perfect" for Le.