(CNN) -- Confused and jittery, students at Yale University plan to hold a vigil Monday as they await word on whether a body found inside a building wall is that of a missing schoolmate.
The remains of a woman were found inside a basement wall at 10 Amistad Street, a medical research building that graduate student Annie Le was seen entering Tuesday morning.
Though authorities have not positively tied the remains to Le, "we are assuming that it is her at this time, so we are treating it as a homicide investigation," said Peter Reichard, the assistant police chief of New Haven, Connecticut.
The mood on the Ivy League campus was a swirl of tangled emotions, said Yale Daily News Editor in Chief Thomas Kaplan.
"Obviously, there're not enough details -- whether it was a random act or something premeditated -- but the sheer news of a body found has freaked some people out," he said early Monday.
"It's just so puzzling how this could have happened. How, whoever did this, could have done it in the middle of the day in a busy building."
Security cameras last captured Le, a 24-year-old pharmacology student, as she entered the four-story lab building, about 10 blocks from the main campus.
Despite poring over hours of surveillance tapes, authorities have not found images of Le leaving the building.
Le was to be married Sunday in Long Island, New York, to Jonathan Widawsky, a graduate student at Columbia University.
"Our hearts go out to Annie Le's family, fiance and friends, who must suffer the additional ordeal of waiting for the body to be identified," Yale University President Richard Levin said in a statement to the campus community.
On Saturday, investigators found bloody clothes hidden behind ceiling tiles at 10 Amistad Street, a law enforcement official said on condition of anonymity. Those clothes were taken in for tests.
A Yale police official told the college newspaper that the clothes were not what Le was wearing when she entered the building, Kaplan said.
On Sunday, investigators searched a waste facility that normally handles garbage from the Yale lab, said William Reiner of the FBI's New Haven office.
He described as routine the search at the Resources Recovery Authority landfill in Hartford, near New Haven.
"In a situation like this, it's common for us to follow the trash," Reiner said.
In December 1998, Suzanne Jovin, a senior political science and international studies double major at Yale, was found stabbed 17 times off-campus. Despite a $60,000 reward, that case remains unsolved.
Le, a resident of Placerville, California, seemed to have been well aware of the risks of crime in a university town.
In February, she compared crime and safety at Yale to other Ivy League schools for a piece for B magazine, published by the medical school.
Among the tips she offered: Keep a minimum amount on your person.
When she walked over to the research building on Tuesday, she left her purse, credit cards and cell phone in her office.