The chief state's medical examiner said Annie Le was killed by asphyxiation caused by neck trauma.
She was found dead inside a basement wall in a Yale medical school research building after several days missing.
Carver had previously announced Le's death as a homicide.
Raymond Clark III was taken into custody Tuesday night at his apartment in Middletown, Conn., and was released into the custody of his attorney early Wednesday after collecting DNA samples and questioning him in Le's death, New Haven police said.
Bloody clothes were said to be found stuffed in a ceiling panel in the Yale lab basement that cannot be attributed to Annie Le, and Raymond Clark's DNA is likely being compared to that evidence at this time.
Investigators are hoping to figure out within days whether Clark can be ruled out as the killer.
A press conference held by the New Haven Police Department is scheduled for later this afternoon with updated information on the Annie Le case.