Details of Disappearance
Cosner was last seen in San Francisco, California on November 2, 1984. He was employed as a used car dealer at the time of his disappearance. His gold or orange 1980 Honda Prelude disappeared with him; a photo of of it is posted with this case summary.
Cosner had advertised the vehicle for sale in the newspaper and told his fiancee he'd found a potential buyer, whom he described as "weird." He said he was leaving his apartment at 7:30 p.m. to meet the buyer and would return at 8:00 p.m. to watch a television show with her. He has never been heard from again.
Police initially believed Cosner left of his own accord and refused to investigate his disappearance. His sister, whom he was close to, never believe he left on his own, however. He had just dissolved a partnership in a used car dealership and expected to receive $35,000 in the deal; he also owned real estate in the area.
Authorities believe that Cosner was a victim of serial killers Charles Chitat (occasionally spelled "Chat") Ng and Leonard Lake. Photos of Ng and Lake are posted with this case summary. The men reportedly met through an advertisement in a survivalist magazine in the early 1980s. Lake was a former United States Marine and a Vietnam War veteran. Ng was a citizen of Hong Kong and falsified American citizenship documents in order to enlist in the Marines.
Ng was charged with stealing weapons from the military in 1982 and was apprehended on Lake's property in California later that year. He was sentenced to 18 months in prison and should have been deported to Hong Kong after completing his sentence, but a bureaucratic error allowed Ng to remain in the United States. He was released in 1984 and moved on to Lake's ranch in Wilseyville, California. Lake was a survivalist and the residence was stocked with weapons, explosives and provisions. Ng and Lake began using the ranch as a veritable sex slave compound shortly thereafter.
Authorities believe that the men found their victims at random. The female victims were often videotaped and forced to perform sexual acts for Ng and Lake prior to their murders. The male victims and children were usually tortured before their deaths.
Investigators apprehended Lake after he and Ng were caught shoplifting from a San Francisco hardware store in 1985. Ng fled from officers, but Lake was taken into custody. The men were driving a vehicle owned by a missing person, who was later determined to have been one of their victims. A pistol and a silencer were discovered inside the car.
Lake swallowed a cyanide capsule he taped to the collar of his shirt while in custody. He reportedly told authorities that Ng was his partner prior to his death several days later. Investigators searched Lake's property and uncovered the remains of several victims, as well as Cosner's eyeglasses, driver's license and car title buried in a plastic drum. Many of the bodies had been dismembered and burned, making identifications of the victims difficult or impossible. Lake's diary made references to Cosner.
Ng was apprehended in Canada later in 1985. He was convicted of eleven murders in California in 1999 after 14 years of legal wrangling and stalling. Ng's trial was one of the most expensive in California history. He claimed Lake was the actual murderer and has never accepted responsibility for the murders. The jury was unable to reach a verdict in Cosner's presumed death, but in 2001 a judge officially ruled that Cosner was one of the victims.
Cosner graduated from Reynoldsburg High School in 1963 and Ohio State University in 1967. He moved to California in 1969. His body has never been located, but foul play is suspected in his case due to the circumstances involved.
Ng and Lake are also believed to be responsible for the 1985 disappearances of Jeffrey Gerald, Clifford Peranteau, and the Dubs family, Deborah, Harvey and their son Sean. All of them vanished from San Francisco and have never been located.