A Costa Mesa police bulletin "wanted" poster shows an artist rendering of a murder suspect from 1976. (Daily Pilot / November 10, 2010)

COSTA MESA — Robyn Cox died violently on a bright winter's day in January 1977.

Murdered the afternoon of Jan. 12, Cox's 5-feet-2, 107-pound body wasn't discovered until that night, when her roommate found it inside their Costa Mesa apartment upon returning home from work.

Cox, 20, appeared to have been strangled or forced to drown in the bathtub, according to a Los Angeles Times article.

The victim was single, had no children and wanted to be a court reporter, but hadn't started studying for that profession, said police Det. Dave Casarez.

What police do know is this: Whoever killed the Coco's Restaurant waitress left investigators little to work with when police reached the crime scene in the 200 block of Avocado Avenue.

Nearly 34 years later, Costa Mesa police are still searching for clues in the unsolved murder. Now, through the Internet, they are turning to the public for help in cracking the Cox case and other cases that have long gone cold.

"All the leads are exhausted and have been," said Costa Mesa police Lt. Paul Dondero.

To jog the memories of potential witnesses, and keep people from forgetting crime victims, starting Friday, Costa Mesa police will be posting details from such cold case files under a new Unsolved Cases section on the department's website, costamesapd.org.

Police will periodically add to the online database of unsolved cases, by putting up photos of victims of unsolved murders, along with contact information for the detectives in the department's cold case unit.

In all there are 23 unsolved homicides in Costa Mesa, a case load that dates back 40 years, along with a slew of other types of unsolved violent crimes.

"We don't want these people to be forgotten," Dondero said. "We'll take anything to start looking in a new direction."

Some cases, like a shooting death in Newport Beach from 16 years ago, reportedly are solved when witnesses, who were once scared to talk to police, are now ready to come forward.

Detectives will start on Friday by posting details online from four murder cases, including the Cox case and the unsolved shooting death of Pamela Davis in 1976.

Davis, 28, was the new mother of a baby. She and her husband lived in the 2800 block of Velasco Lane, and were trying to sell their house. It was foggy and drizzly on Sept. 10, 1976, when a man wearing thick, black-rimmed glasses with thick lenses and a three-quarter length overcoat, and whose hair was nicely combed, entered the Davis home. Only the woman and a little boy, who was her relative, were in the house, police said.

There's no evidence that the man broke in, as Davis was showing the single-story house to prospective buyers, police said. It's possible that he used a ruse to get inside, authorities said.

Relying on evidence and the child's account, police said the man shot Davis to death in her bedroom. The boy came out of another room when he heard the shots and saw the killer standing in the bedroom doorway, so he ran to a neighbor's house and called police. There was no 9-1-1 back then.

Detectives canvassed the area and found only two other witnesses: a pair of juveniles who had seen the killer approach the house. Police described the killer as a 27-year-old white man, 6 feet tall with a thin build, short black hair parted to the left with short sideburns, a pale complexion and dark trousers and shoes.

No one saw the killer leave.

The department's cold case unit counts three detectives: two retired police veterans, Dets. Bob Fate and Ed Zuorski, who work part time, and Casarez. One by one, these investigators dust off each case, comb all the evidence, interview all the witnesses and look for new leads. They also work on other unsolved violent cases, such as shootings and robberies. Anyone with information on unsolved Costa Mesa cases, which will be featured at costamesapd.org, should call the detectives' bureau at (714) 754-5205.