On this day in 2011, 26-year-old Raymond Clark III, a former animal research assistant at Yale University in New Haven, Connecticut, pleads guilty to the murder and attempted sexual assault of 24-year-old Yale graduate student Annie Le. On September 13, 2009, Le’s partially decomposed body was found stuffed behind a wall in the university research building where she was last seen five days earlier.

Le, a doctoral student in pharmacology from Placerville, California, was found dead on the day she was scheduled to be married, prompting initial speculation after her September 8, 2009, disappearance that could be a runaway bride. However, that theory soon appeared to be largely ruled out by investigators. Surveillance video showed Le entering the Yale lab building, which was accessible only by electronic keycard, but never leaving it. Her money, cell phone and ID were found in her office, located in a separate building.

Le’s disappearance set off a massive investigation that included more than 100 officers from university, state and local police and the FBI. The case also garnered national media attention. A break came on September 12, when investigators found bloody clothing above ceiling tiles in the lab building. The following day, Le’s body was discovered behind a wall in the building’s basement. It was determined the 4-foot-11-inch, 90-pound Le had been strangled.

Middletown, Connecticut, resident Raymond Clark, who cared for the animals in the lab where Le worked, soon sparked the suspicions of police after he was observed scrubbing the seemingly clean floor in the room where Le was last seen. On September 17, police arrested Clark, after finding DNA and other evidence they said linked him to the crime. Among the evidence was a bloody sock with both Clark’s and Le’s DNA on it, as well as a pen found under Le’s body with Clark’s DNA. Additionally, investigators discovered scratches on Clark’s body (which he claimed were from a cat), and found keycard records placing him and Le in the same room in the lab building on the day she was reported missing.

In January 2010, Clark pleaded not guilty to murder. However, on March 17 of the following year, after negotiations between the prosecutor in the case and Clark’s lawyers, the former lab technician pleaded guilty to charges of murder and attempt to commit sexual assault, in order to avoid a trial. He did not specify a motive, and the reason for his actions remains unclear. On June 3, 2011, Clark was sentenced to 44 years in prison without the possibility of early release.