Federal prosecutors say a man charged with shoving his second wife over a cliff in Rocky Mountain National Park told wildly varying stories about her death and the death of his first wife.

In a motion Thursday, prosecutors asked a judge to allow them to present a raft of evidence at trial.

Harold Henthorn, 58, is charged with first-degree murder in the 2012 death of his wife, Toni Henthorn. In that case, authorities found a map in Henthorn’s Jeep with an X marking the cliff near where she fell.

U.S. Attorney John Walsh’s office filed a motion in U.S. District Court asking for permission to present evidence at Henthorn’s trial linked to the suspicious death of his first wife, Sandra “Lynn,” 37, who died in 1995. The motion also says Henthorn forged his sister-in-law’s signature on another life insurance policy.

Meantime, Douglas County Sheriff Tony Spurlock announced Thursday in a news release that his investigators are conducting a thorough investigation into the death of Lynn Henthorn.

“Over the past 27 months of the investigation, approximately 40 interviews have been conducted and additional information has been uncovered that was unknown and or unavailable at the time,” Spurlock’s news release says.

Both cases involving Henthorn’s wives include bizarre “accidents,” left Henthorn with “significant” insurance benefits and occurred in remote locations where he was the lone witness. Henthorn told wildly varying stories about both deaths and both women were doing atypical things when they died, the motion says.

“In both cases Harold was eager to have the bodies quickly cremated despite family requests against it and Harold spread both women’s ashes on the same mountain near Ouray, Colorado,” the document says.

On Sept. 29, 2012, Henthorn told authorities his wife was climbing down a remote, sheer cliff, even though she had bad knees, and fell. Toni was insured by three life insurance policies totaling $4.5 million.

Lynn Henthorn was killed while she was helping her husband change a flat tire near Sedalia on Colorado 67. She inexplicably had climbed under the car while wearing a nice sweater only two weeks after undergoing surgery. Henthorn received $500,000 from three life insurance policies including one taken out four months earlier.

“Given the similarities between the two murders and the scarcity of other evidence on point, the death of Lynn Henthorn is highly probative of Harold’s intent, motive, planning, and lack of accident in killing his second wife,” the motion says.

The motion also presents new details in the 1995 case. It says while they were changing a tire, Henthorn “oddly turned away a car that offered to shine its lights on the scene.”

“The rejection of help and the remote location support an inference that Henthorn sought to avoid witnesses,” the motion says.

Henthorn told law enforcement that because his car jack was not working properly, he had used two boat jacks to lift the Jeep. Lynn held a flashlight and the lug nuts while Henthorn changed the tire. When he later threw the low tire in the back of the car, the car fell off the jacks. He heard Lynn call for help and found her pinned underneath the car.

“In this case, the deaths of Henthorn’s wives taken individually could have been accidents. But, taken together, the doctrine of chances removes that possibility,” the motion says. “It is objectively implausible that both of Henthorn’s wives would die in bizarre accidents in remote areas where he was the lone witness and beneficiary of their life insurance.”

Henthorn eventually flagged down another car. He initially told them not to touch his wife and tried to stop them from performing CPR. Because it was cold outside, the responders put their coats on Lynn. Harold was wearing a coat, but had not covered his wife.

The motion says a jury could find by the preponderance of evidence that Henthorn killed his first wife.

“[I]t is not every day that one’s wife is murdered,” the motion says.

The motion also says Henthorn did the paperwork on a life insurance policy for the life of his former sister-in-law Grace Rishell in 2009. The policy listed Rishell’s daughters as beneficiaries of the $250,000 policy.

Though Rishell told insurers in 2010 that she no longer wished to have the policy, she learned that Henthorn had forged her signature on insurance documents. He paid for the policy, which was switched to make him the beneficiary, for two years. The policy was canceled in 2013 when the insurer concluded Henthorn had no insurable interest in Rishell, the motion says.

The motion also seeks to admit evidence of an incident that happened about a year before Toni’s death in which Henthorn dropped a 20-foot wooden beam on her.

Toni Henthorn told medical personnel that her husband “was chucking plywood over the deck” and she could not get out of the way of the piece that hit her, the motion says.

But since the beam hit Toni in the back of her neck, she was relying on her husband’s account of whether the beam was dropped, thrown, or simply fell on her. And he had many accounts, the motion says.

Henthorn told medical personnel that he did not know Toni was there and had been blindly tossing wood off the deck. The Henthorns told others that the board simply fell from the deck. Henthorn later told family members and friends that he had been working on a ladder when he fell and dropped the beam on Toni or the beam slipped from his hands while he was standing on the ladder. He told another witness that Toni was holding the ladder for him when the board fell.

Henthorn told one friend in a joking manner, “I was trying to kill my wife.”

“It was an odd joke for someone who had already lost his first wife in tragedy,” the motion says.

Kirk Mitchell: 303-954-1206, denverpost.com/coldcases or twitter.com/kirkmitchell

This story has been updated in this online archive. An earlier version incorrectly characterized the relationship between Harold Henthorn and Grace Rishell.