It was in the early hours of a crisp May morning in 2008 when Leslie and Fred Mueller, a seemingly happy Texas couple, set out for a scenic hike near their Colorado vacation home in Cottonwood Creek. The couple, together for years, had traveled to this spot numerous times. But this hike would be their last together, ending in a tragedy that would spawn years of speculation, two murder trials, and no answers that ever quite seemed to fit. Leslie Mueller’s life ended that day—but the mysteries surrounding her death had only just begun.

Fred Mueller recounted the events of that morning to investigators, claiming that while they were taking photos near a cliff edge, Leslie was startled by a bird. In a sudden, terrifying moment, he said, she lost her balance, stumbled backward, and fell off the cliff, “swan diving” into the freezing waters below. Fred frantically climbed down to the creek to help her but was unable to find her body which rushed away in the water. Panicked, he left to find help, but when rescuers arrived, Leslie Mueller’s body was floating 50 feet down stream. Leslie Mueller, mother of three and beloved community member, was dead. 

It appeared to be a terrible, tragic accident. But like a bad math problem, things weren’t adding up. Leslie’s injuries, or rather the lack of them, baffled investigators. There was a “significant absence of any visible injury to any part of the body.” She had no broken bones, scrapes or bruises that would have been expected after a 20-foot fall onto rocks. The autopsy revealed she had drowned, but the depth of the water where she fell would have kept her body in place, not drifting downstream as Fred claimed for his inability to rescue her. Fred also bore scratches on his face, which suggested to authorities there could have been a struggle at some point—it didn’t help Fred’s glasses were found broken 15 feet from where Leslie fell.   

Investigators soon developed a theory: perhaps Fred, a respected and well-off businessman, might have pushed her off the cliff or even held her in the water until she drowned. Afterall, how could someone really fall from such a height with so few injuries? And why was Fred, by his own admission, so slow to seek help? Fred denied all allegations, insisting he would never harm his wife and that her death was a tragic accident. 

In 2012, authorities believed they had enough evidence to convict Fred Mueller for the crime of killing his wife. He was arrested and charged with murder, accused of orchestrating his wife’s death to collect on her life insurance and escape a reportedly struggling marriage. At trial, Fred’s defense would argue the allegations claiming they were based on nothing more than circumstantial evidence. There were no witnesses to confirm any version of events, and no physical evidence irrefutably tied Fred to Leslie’s death. His lawyers argued that the scratches on his face were simply from navigating the rugged terrain while trying to reach his wife. As for her drowning? It was May runoff season at the time and water levels fluctuated drastically, something prosecutors didn’t account for in their investigation. Finally, Fred’s three children take the stand; portraying their dad as a loving father and husband, not a killer. 

Five weeks into the trial, prosecution and defense rest their cases and the jury begins deliberations. Eight days later, the judge declared a mistrial due to the inability of the jury to reach a verdict. The trial ended in 2013 with a hung jury, unable to reach a unanimous decision. Jurors were divided, torn between the chilling possibility of a deliberate act and the lingering doubt that it could have been a freak accident. Prosecutors weren’t having it, and filed yet another trial in the same year; the outcome led to a similar result—another hung jury, with a narrow majority leaning toward conviction but not enough to seal a guilty verdict. After years of trials, testimonies, and public intrigue, a judge dismissed the case, citing insufficient evidence to retry it a third time. Fred Mueller returned to Texas, remarrying two years after the dismissal, and resuming his life as a businessman. We will never know what happened at Cottonwood Creek that May morning and it’ll be forever shrouded in mystery of what Leslie Mueller’s final moments looked like.