A Sacramento man has been accused of killing two British tourists on a boating excursion from Belize 38 years ago.

The Sacramento Bee reports that 75-year-old Silas Duane Boston is awaiting trial for two counts of first-degree maritime murder in the 1978 killings of Christopher Farmer and Peta Frampton, both in their mid-20s. He was arrested Dec. 2 and has pleaded not guilty.

Prosecutors say Boston, the operator of a tour boat, beat Farmer with a billy club before tying the couple up and throwing them overboard. Their bodies were found off the coast of Guatemala.

Farmer’s 92-year-old mother, in a letter introduced in federal court Tuesday, called for a speedy trial after waiting all these years to see justice for her son.