NEW HAVEN, Conn. — 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 and from Clark’s Middletown, Conn., apartment.

Police served two search warrants — for DNA from Clark and for items in his apartment — late Tuesday. They served two more Wednesday morning, for more items from the apartment and for Clark’s Ford Mustang, Police Chief James Lewis said.

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. He said police expect to seek an arrest warrant for anyone whose DNA matches evidence at the crime scene.

Clark is not talking to police, Lewis said.

“At some point he may be willing to answer questions, but at this point he has invoked his rights,” Lewis said. “He has an attorney. We couldn’t question him if we wanted to.”

Clark’s attorney, David Dworski, said his client is “committed to proceeding appropriately with the authorities.” He would not elaborate.

A police lab is expediting tests on Clark’s DNA. University of Connecticut genetics professor Linda Straus Baugh says testing can be done in days if a case gets top priority.

Clark’s job as an animal-services technician at Yale would probably put him in contact with Le, who worked for a Yale laboratory that conducted experiments on mice. She was part of a team researching enzymes that could have implications for cancer, diabetes and muscular dystrophy treatment.

Clark, his fiancee, his sister and his brother-in-law all work for Yale as animal lab technicians.

Le’s body was found Sunday stuffed behind the wall of the basement where lab animals are kept. The Connecticut state medical examiner said Wednesday that Le died of “traumatic asphyxiation.”

Authorities released no details on how she died, but traumatic asphyxiation could be consistent with a choke hold or some other form of pressure-induced asphyxiation caused by a hand or an object, such as a pipe.