A Fallbrook man accused of gunning down his parents 25 years ago wants a judge to toss the murder charges he faces, in part because there is no new evidence and some key witnesses are now dead.

David Andrew Boysen, 48, was arrested in May, nearly a quarter-century after the 1980 slayings of his parents, Robert and Elsie Boysen.

Defense attorney Daniel Davis argued in recently filed court documents that David Boysen's delayed arrest —— which came in May, more than 24 years after the slayings —— has undermined Boysen's right to a speedy trial.

Prosecutor Jeff Dusek could be reached for comment Monday evening. His response to Davis' motion to dismiss is due to the court this week.

Davis declined to comment, citing the gag-order handed down by Judge Joan Weber on the case.

In his written motion, Davis argues that the "unconstitutional and unjustified" delay in the case is costing Boysen the ability to fairly defend himself.

"Police reports have been misplaced, lost or never even prepared. Leads that might have exculpated David Boysen were never competently followed up. Critical pieces of evidence … are now unavailable. Critical witnesses are now dead." Davis wrote in his motion asking Judge Joan Weber to dismiss the charges.

Boysen's parents were found shot to death on Easter Sunday in 1980 in their Avocado Drive home in Oceanside. Elsie Boysen also had been bludgeoned, and a broken and splintered wooden handle was found near her body.

Police last shelved their investigation in 1982.

Last year, Oceanside police and the district attorney's Cold Case Unit, which was created to crack old cases, reopened the Boysen case and arrested David Boysen in May. There are no statutes of limitation for murder charges.

In his motion to dismiss the case, Davis argues that authorities have garnered no new evidence in the slaying since 1982.

Davis attacks the credibility of the prosecution's star witnesses, Boysen's ex-wife, who was his alibi on the night of the slayings. In 1982, she recanted a portion of Boysen's alibi and has implicated Boysen.

Boysen has pleaded not guilty to two murder charges, and has denied allegations that he killed his parents for financial gain and committed multiple murders. He faces life in prison if convicted on all charges.

Weber is set to hear the matter May 6.

Contact staff writer Teri Figueroa at (760) 740-3517 or tfigueroa@nctimes.com.