PASADENA -- The Cal State Los Angeles professor found murdered and mutilated in her home Monday morning had been stabbed more than 30 times and suffered a severe blow to the head, according to autopsy results released Thursday.

Coroner's officials say Glenda Vittimberga, 37, died from the injuries, and was most likely beheaded after she was already dead.

The Los Angeles County Coroner's Office also confirmed that the prime suspect in the slaying, Mark Stephen Guerrero, committed suicide.

In the hours after Vittimberga was killed, Guerrero, 38, drove his car to a remote area on Interstate 15 where he parked, stripped off his clothes and stepped in front of a passing Peterbilt tractor-trailer truck.

Coroner's officials say the results of the toxicology screens on Guerrero and Vittimberga should be available in six to eight weeks.

Police detectives said they have yet to determine a motive for the killing, but have found evidence at Guerrero's West Covina home that he and Vittimberga had been romantically involved. Guerrero lived with his parents, police said.

Detectives said the two had ended their relationship, but would not say if it was considered a motive in the murder.

Vittimberga's friends have denied the two were involved in a romantic relationship.

Vittimberga and Guerrero apparently met at Cal State L.A., where the two worked together in the education department's diagnostic resource center.

Guerrero was a graduate student instructor at the center and Vittimberga was the supervisor.

Though he was a convicted felon, Guerrero lied on the college's employment application, saying he did not have a criminal history. University officials now say they are reviewing hiring procedures.

"The university is committed to providing the greatest safety to our campus community without compromising the privacy rights of its employees,' the university said in a press release Thursday.

University spokeswoman Carol Selkin said there was no indication Guerrero had displayed any threatening or aberrant behavior while at the college, and was considered a good student, carrying a 3.8 grade point average. He had been accepted in a master's degree program in psychology, having earlier earned a master's in education at the university.

Police went to Vittimberga's home early Monday morning after receiving a phone call from Guerrero's sister. She told the officer her brother had contacted her to say he was depressed and indicated something might be wrong with Vittimberga.

Officers went to Vittimberga's home in the 1100 block of Medford Road and forced their way in when no one answered the door.

Vittimberga's body was found in the kitchen and her head in the living room fire place.

Pasadena police Lt. Randell Taylor said police have no reason to suspect anyone but Guerrero was involved in the slaying. Blood found in his car is being tested to determine if it is Vittimberga's.

Students at Cal State LA are planning a candlelight vigil for Vittimberga at 6 p.m. Tuesday in the free speech area.