Prosecutors allege that a man accused of pushing his second wife to her death off a cliff during a scenic hike in Colorado's Rocky Mountain National Park might have killed his first wife in what also appeared to be a freak accident nearly 20 years earlier.

They will make that argument when a federal trial for 58-year-old Harold Henthorn opens Tuesday.

Investigators charge that he shoved his second wife, Toni Henthorn, 140 feet off a cliff in a remote area the couple had been hiking on Sept. 29, 2012. They were celebrating their 12th wedding anniversary.

Prosecutors say Toni's fall was reminiscent of the death of Henthorn's first wife, Sandra Lynn, in 1995. She was crushed when a car slipped off a jack as she changed a flat tire.

Henthorn's attorney Craig Truman says the deaths were accidents.