Before there was blood, the high-tech lab at 10 Amistad Street at Yale University was a model of efficiency. The mice and rats and rabbits stayed locked in cages. The technicians responsible for their well-being circulated like emergency room nurses. Researchers hunched over the cages for hours, intent on claiming a breakthrough.

The two groups interacted in professional if perfunctory ways, but on Thursday, the authorities charged a technician, Raymond Clark III, with murdering one of the graduate researchers, Annie M. Le. Ms. Le, 24, was strangled on Sept. 8, and her body was found on Sunday hidden behind a wall, out of view from the immaculate corridors of the lab.

Mr. Clark, 24, was arrested just after 8 a.m. Thursday in Room 214 of the Super 8 Motel in Cromwell, Conn. He had been staying there with his father, at the end of several days in which the authorities interviewed him, tailed him, took DNA samples and then kept him under surveillance. He was charged with murder and driven back to New Haven, where he was arraigned but said little and did not enter a plea. Bail was set at $3 million.

The authorities said his DNA matched crime scene evidence, but did not elaborate.

Chief James Lewis of the New Haven police would not speak about a possible motive, but said, “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.”