EL DORADO COUNTY, Calif. -- Investigators are asking the public to help close the nearly 40-year-old unsolved murder case of a California man.

Berkeley native Lee Hassler was 36 when he was gunned down on Oct. 6, 1976. His murder is among the dozens of cold case homicides in El Dorado County, Calif. that a special task force is aiming to solve. The task force was launched by county district attorney Vern Pierson in 2013 in an effort to close the more than 60 cold case murders in the county of 180,000 - nearly double the amount of cold cases as nearby counties twice its size, according to DA Pierson's office.

As a part of that effort to solicit tips from the public, the office is developing a series of videos highlighting each of the cases and releasing them monthly on their Facebook page. 48 Hours' Crimesider is reporting on the cases and posting the videos.

Hassler received a bachelor's of economics from the University of California at Berkeley in 1968 and later worked in a series of jobs - including in real estate sales and as a bar owner, according to family. In a 1970 application to Cal Berkeley's MBA program, he wrote about his goal of advancing in the "fields of investment counseling in both real estate and securities."

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Hassler was also involved in Judo and had earned his black belt in the martial art, according to family.

In 1974, Hassler moved to Germany, and his younger brother Glen told 48 Hours' Crimesider he was involved with shipping chemicals used in illegal drugs to the United States. In early October of 1976, Hassler returned to the U.S. in order to resolve a financial dispute, according to police.

He was last seen just days after his return at his mother's home in Berkeley on Oct. 5 of that year. His body was discovered by hikers the next day - it had been dumped over the side of Highway 50 near Whitehall, nearly 150 miles east of Berkeley. No suspects have ever been identified.

Police are asking anyone who has information about Hassler's murder to come forward. Tipsters can call 530-903-8468 or email robert.cosley@edcgov.us.