Dr. William Massello, the assistant medical examiner based in Roanoke, said pathologists have sent blood samples for toxicology testing to determine if Cho was on drugs at the time of his rampage. It could take as long as two weeks to get the results of those tests, he said.
Cho was not especially accurate with his shots, Massello said, but hit many of the victims several times. His shots caused more than 100 wounds.
He picked up his first gun on February 9th from a pawn shop near campus, reports CBS News correspondent Sharyn Alfonsi.
Days later, he started shopping over a series of days, picking up cargo pants, a hunting knife, gloves, ammunition and chains to lock the doors of Norris Hall shut.
Investigators say he fired more than 175 rounds inside that classroom, adds Alfonsi.
Many of the victims had defensive wounds, indicating they tried to shield themselves from Cho's fire, but there was no evidence in the autopsies that Cho struggled with any of the people he killed.
Cho died from a gunshot to his temple, Massello said. Even if his brain had been intact, doctors would not have been able to tell whether he had any sort of brain abnormality. Those are usually neurological or chemical disorders that are not detectable during an autopsy, he said.
Massello said autopsy reports are being typed, and he was unsure when they would formally be completed and released.
Authorities had to return to the victims' dorm rooms and homes to collect fingerprint information so they could make identifications, according to an official close to the investigation who spoke on condition of anonymity because the investigation is ongoing.
Several of the victims had gunshot wounds to the head, the official said.
Many of the victims' bodies left the medical examiner's office on Thursday, the official said, adding that several major airlines offered to transport the bodies back to their families' for free. The official was not sure if Cho's body was among those that had been released.
Massello said it took four doctors working for days to complete the autopsies on all 32 victims and Cho, but he was not sure whether all had been released to families.