Police on Monday sought to calm fears on the Ivy League campus, saying the death of 24-year-old Annie Le was a targeted act but would not say why anyone would want to kill the young woman just days before she was to be married.
"We're not believing it's a random act," said officer Joe Avery, a police spokesman. No one else is in danger, he said, though he would not provide details other than to say that police believe no other students were involved. He also denied broadcast reports that police had a suspect in custody.
Yale officials said the building where Le worked would reopen under increased security. Still, some students worried about their safety.
"I'm not walking at nights by myself anymore," said student Natoya Peart, 21, of Jamaica. "It could happen to anyone, anytime, anywhere."
Michael Vishnevetsky, 21, of New York, said he did not feel safe when he made a late trip to his lab Sunday in a different building. "It felt very different than how I usually felt," he said.
Twenty-year-old Muneeb Sultan said he's shocked that a killing could take place in a secure Yale building.
"It's a frightening idea that there's a murderer walking around on campus," said Sultan, a chemistry student.
Police found Le's body about 5 p.m. Sunday, the day she was to marry Columbia University graduate student Jonathan Widawsky, lovingly referred to on her Facebook page as "my best friend." The couple met as undergraduates at the University of Rochester and were eagerly awaiting their planned wedding on Long Island.
Police have said Widawsky is not a suspect and helped detectives in their investigation.
The building where the body was found is part of the university medical school complex about a mile from Yale's main campus. It is accessible to Yale personnel with identification cards. Some 75 video surveillance cameras monitor all doorways.
The body was found in the basement in the wall chase - a deep recess where utilities and cables run between floors. The basement houses rodents, mostly mice, used for scientific testing by multiple Yale researchers, said Robert Alpern, dean of the Yale University School of Medicine.
Le was part of a research team headed by her faculty adviser, Anton Bennett. According to its Web site, the Bennett Laboratory was involved in enzyme research that could have implications in cancer, diabetes and muscular dystrophy. Bennett declined to comment Monday on the lab or Le's involvement with it.
Le's office was on the third floor of the five-story building, where authorities found her wallet, keys, money and purse. Campus officials have said that the security network recorded Le entering the building by swiping her ID card about 10 a.m. Tuesday. She was never seen leaving.
Yale closed the building Monday so police could complete their investigation, according to a message sent to Yale students and staff. Scientists are being allowed in only to conduct essential research projects, and only under the supervision of a police officer.
Police activity continued at the crime scene early Monday evening, as uniformed officers with police dogs and workers wearing white suits to protect them from hazardous materials went in and out of the building.
When the building reopens, there will be extra security both inside and outside, said Yale Secretary and Vice President Linda Lorimer.
Police are analyzing what they call "a large amount" of physical evidence.
A friend said Monday that Le never showed signs of worry about her own personal safety at work, though she did express concerns about crime in New Haven in an article she wrote in February for the medical school's magazine.
"If she was concerned about (it) she would have said something to someone, and they would have known," Jennifer Simpson told CBS' "The Early Show." "And Jon (her fiance) would have known, her family would have known, friends would have known."
Simpson said Le, a pharmacology student from Placerville, Calif., was friendly to everyone.
"She was a people person," Simpson said. "She loved people. She loved life. We just can't imagine anybody wanting to harm Annie."
In the Sierra foothills community east of Sacramento where Le went to high school, she was seen as a high achiever who knew early on that she wanted a career in medicine.
In a Union Mine High School yearbook from 2003, Le said her long-term goal was to become a laboratory pathologist and said it would require about 12 years of higher education.
"I just hope that all that hard work is going to pay off and I'm really going to enjoy my job," she said.
No one answered the door Monday at the Widawskys' gray, ranch-style home in Huntington, N.Y.
"He is a very nice young man," next-door neighbor George Mayer said of Jonathan Widawsky, a 24-year-old seeking his doctorate in physics. "His family, they're all just wonderful people - very, very nice people."
The university planned a candlelight vigil for Monday evening.
The death is the first killing at Yale since the unsolved December 1998 death of Yale student Suzanne Jovin. The popular 21-year-old senior was stabbed 17 times in New Haven's East Rock neighborhood, about 2 miles from campus.