Los Angeles (CNN) -- Investigators have identified two men shown in a video apparently sexually assaulting disabled women in a care home and other places, Los Angeles Country sheriff's detectives told CNN Friday.
One suspect is Bert Hicks, 41, who is now serving a state prison sentence in Tehachapi, California, for fiduciary crimes, abuse and sexual assault in a residential care facility, said sheriff's Detective Ron Anderson.
Hicks allegedly took a disabled woman to Las Vegas, married her and then brought her back to the care facility, where she was repeatedly sexually assaulted by other men, Anderson said.
Authorities don't know if the crimes Hicks was convicted of are the ones depicted on video, Anderson said.
Sheriff's investigators announced their investigation into the video Thursday, when they issued a public appeal for help because the video was mailed to them by an anonymous tipster.
City of Los Angeles police detectives saw Thursday's media coverage and told the sheriff's office that they could identify two of the four suspects shown in composite sketches, Los Angeles County Sheriff's Sgt. Dan Scott told CNN.
Hicks and the other suspect were under investigation by Los Angeles police in 2007 and 2009 cases, Scott said. The other suspect identified by Los Angeles police was never charged because of a lack of evidence, but authorities know where he is, Scott said.
The 13 DVDs mailed by the anonymous tipster to the sheriff last March contain more than 100 hours of video of at least 10 men apparently sexually assaulting at least eight severely disabled women in a care home and several other locations, according to Scott and Anderson.
Sheriff's investigators spent months reviewing the grainy video and were able to come up with composites of only four of the 10 suspects, authorities said.
Investigators believe the sexual assaults occurred in the past three to five years, Anderson said.
The identification of two suspects was considered a major break in the case because the leads could allow authorities to determine the other eight suspects and the locations of the alleged rapes, authorities said.
"The puzzle is being put together," Scott told CNN. "We believe we are now going to be able to identify all the suspects."
Authorities have received many phone calls from southern California residents who are concerned that the alleged victims are loved ones in a care home, Scott said.
The sheriff's department has made their inquiries "a high priority," Scott said.
"We've got people in Los Angeles County who are worried about their relatives," Scott said.
Authorities are still asking for the tipster to come forward -- even anonymously, by contacting a hotline -- and provide more details on the video.
A "To Police" letter accompanying the video states that the tipster was a computer technician who was hired by a man to wipe clean a hard drive on a laptop that the man bought for $20 from a "crackhead" on a street in Inglewood, California, Anderson said.
When the computer technician saw the video, he was so disturbed that he made copies on the 13 DVDs and mailed them to the sheriff, Anderson said.
In the letter, the technician said the laptop purchaser was also aware of the video content.
Authorities allowed CNN to see the letter, which contains grammatical errors. It says in part:
"He saw what was on the hard drive and ask could I wipe it and restage Windows, etc. I did restage but I have to copy this stuff for a police action.
"The video's found on the hard drive was disturbing and made me sick. I had to turn it in and I pray that you find these (expletives) in the video's molesting handicap people," the letter says.
Authorities said the graphic video even depicted one woman victim in a wheelchair who was wearing a diaper.
The suspects allegedly sexually assaulted "people in bed unable to move. They can't pick up the phone," Scott said.
Added Anderson: "I've seen a lot of terrible, terrible imagery in my assignment, that involved children and all kinds of hideous things. This is among the most heinous I've ever seen. ... What I saw was just these poor people lying there being victimized in the most terrible way I've ever seen."
The video was shot by a security camera and a handheld camera, Scott said.
At Thursday's news conference, Sgt. Diane Hecht told CNN that detectives are "starting from scratch" in their inquiry.
"This is extremely serious. These women are developmentally disabled. It's awful to take advantage of anyone, but especially someone who could not defend themselves," Hecht said.
Detectives asked the tipster to call the anonymous Crime Stoppers communication system at 800-222-8477 and provide details on the video's origin. Investigators said the public can also call the special victim bureau's hot line at 866-247-5877. Information can also be provided anonymously by texting the letters TIPLA plus the tip to CRIMES (274637) or by accessing the Crime Stoppers website at www.lacrimestoppers.org.
CNN's Paul Vercammen contributed to this report.