Connecticut ? A Yale graduate student found stuffed in the wall of a research center had been suffocated, the medical examiner reported Wednesday as police awaited DNA tests on evidence taken from a lab technician who worked in the building.

Police call Raymond Clark III a “person of interest” in the slaying of Annie Le. Authorities hoped to compare DNA taken from Clark’s hair, fingernails and saliva with more than 250 pieces of evidence collected at the crime scene on the Ivy League campus in New Haven, Conn., and from Clark’s Middletown, Conn., apartment.

“It’s all up to the lab now,” Police Chief James Lewis said at a news conference. “The basis of the investigation now is really on the physical evidence.”

Police late Wednesday were watching a hotel room in Cromwell where a “person of interest” in the killing had been staying, Cromwell Police Capt. Roy Nelson said. Broadcast reports said Clark was staying at the hotel.

Investigators said they expect to determine within days whether Clark should be charged in the killing. He was escorted in handcuffs from his apartment and released early Wednesday into the custody of his attorney, police said.

Lewis said Clark and several other people are under constant police surveillance.