LOS ANGELES -- The parents of the first three victims of Elliot Rodger's murderous rampage in Santa Barbara say they're frustrated by authorities' handling of the case.

The bodies of James Hong, David Wang and George Chen were found inside a beachside apartment the night Rodger went on a killing spree near the University of California, Santa Barbara campus, fatally shooting three at random, injuring 13 others before taking his own life.

It's not clear how the slightly built Rodger was able to overpower the three and stab them to death. Rodger was randomly assigned to share the Isla Vista apartment with Hong and Wang. Chen was visiting the pair on May 23.

In a joint interview, the victims' parents told the Washington Post that they visited the crime scene and saw no blood on the walls or ceiling. Police had removed a 6-by-5 foot piece of carpeting in one bedroom and a swath of vinyl flooring around the toilet had been cut. They said the limited amount of material removed from the apartment suggest the killings were confined to a small space.

They criticized the Santa Barbara Sheriff's department for not telling them how they believe the killings were carried out, and said they are angered by public health and legal systems that they said value the rights of the mentally ill, including Rodger, over those who may become their victims.

"The system is clearly broken," said Hong's father, Henry Hong. "It should have protected our sons, who were so innocent and trusting."

Sheriff's spokeswoman Kelly Hoover said in a statement that the department "owes it to the victim's families and to the public to not prematurely release information before we have all of the facts in this case."

Sheriff Bill Brown has said the men were stabbed repeatedly with sharp objects and called the crime scene "pretty horrific."

The Los Angeles Times reports the men met through their computer engineering classes at UC Santa Barbara, shared a passion for math and science and dreamed of creating a start-up together after graduation. They had each moved from the Bay Area and were the sons of Chinese immigrants.