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Mark Newby called 911 on April 4, 2008, to report that his wife had been thrown from her horse and had gone over a cliff as the couple rode in Rocky Canyon, a remote stretch of the Boise Foothills in Ada County, Idaho. Susan Newby, 53, was dead at the scene.

The dispatcher who fielded the call was not familiar with the rugged canyon and needed several minutes to fix the couple's location so deputies and medics could reach it. The dispatcher stayed on the line with Newby for about 29 minutes.

The death first looked like an accident, Ada County Sheriff Gary Raney said. Sue Newby was an information technology professional and a lifelong rider who kept Arabian horses, and she had gone over a drop of roughly 100 feet. Footprints at the scene gave detectives little to work with.

Over the following weeks, investigators in the sheriff's Major Crimes Unit built a different picture. Raney said Mark Newby had made significant financial arrangements, among them life insurance, that stood to benefit him if his wife died. The day after her death, according to the sheriff, Newby began an intimate relationship with another woman and spoke of the death in flippant terms. Court records showed he had been arrested in 2003 on a domestic battery allegation involving an earlier wife.

Sue Newby's riding companions doubted the account that her horse had bucked her off, telling investigators the animal was known to bolt when spooked but not to throw its rider. 'We developed probable cause and we would have charged Mark Newby for pushing her off a cliff,' Raney said.

Deputies obtained a warrant and moved to search the couple's home in Meridian in May 2008. Just after midnight, as officers arrived to serve it, Newby shot himself with a small handgun in a bedroom. Ada County Coroner Erwin Sonnenberg said he died of a gunshot wound to the head at 12:45 a.m. No one was ever charged in Sue Newby's death.

Friends who had ridden with her later placed a cross in the canyon at the spot where she went over the edge.