DENVER (CBS4) – A federal judge has ruled that prosecutors will be allowed to tell a jury about the death of Harold Henthorn‘s first wife in 1995 when the Highlands Ranch man goes on trial for the death of his second wife.

In an 18 page ruling released Friday morning, U.S. District Judge R. Brooke Jackson overruled defense objections and wrote that a jury will be allowed to hear about the death of Lynn Henthorn, 17 years before the death of Henthorn’s second wife.

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“There is sufficient evidence to support a reasonable finding by a jury that it is more likely than not that Lynn Henthorn’s death was not an accident but instead a murder,” wrote Jackson.

Harold and Sandra Lynn (courtesy to CBS)

Harold and Sandra Lynn (courtesy to CBS)

Harold Henthorn is slated to stand trial in September for the 2012 death of his second wife, Toni Henthorn, who fell to her death in Rocky Mountain National Park during a hike with her husband.

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He said it was an accident but federal prosecutors charged him with murder. As part of that upcoming trial, prosecutors sought to persuade the judge to allow the jury to hear about what they considered prior bad acts by Henthorn. That included the death of his first wife Lynn, who died during a tire change when the couple’s Jeep fell on her.

Harold Henthorn maintained it was an accident when a jack failed while his wife was getting a lugnut that had rolled under the car. Douglas County investigators ruled that case an accident and Henthorn was never charged. The case has now been reopened.

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Harold and Toni Henthorn (credit CBS)

Harold and Toni Henthorn (credit CBS)

“The Court finds that evidence concerning the death of Lynn Henthorn is admissible,” wrote Jackson.

The Judge also ruled that the jury can hear about a 2011 incident in which Henthorn said he accidentally dropped a beam or piece of plywood that badly injured Toni Henthorn.

Prosecutors contend that was Henthorn’s first attempt to kill Toni Henthorn.

“If Mr. Henthorn was determined to kill his wife, dropping a board on her strikes me an odd way to attempt it,” wrote Jackson. “The Court concludes that a jury could reasonably find by a preponderance of the evidence that the deck incident was not an accident, but rather a deliberate attempt to bring about his wife’s death.”

In a minor victory for Henthorn’s defense team, Jackson ruled that prosecutors will not be allowed to tell the jury about an insurance policy Harold Henthorn took out on his ex- sister in law, Grace Rishell.

“I conclude that it is not relevant to the actual crime charged,” wrote Jackson. “It is not probative of Mr. Henthorn’s common plan or motive to murder Toni Henthorn.”

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CBS4 Investigator Brian Maass has been with the station more than 30 years uncovering waste, fraud and corruption. Follow him on Twitter @Briancbs4.