In December 1978, the frost had crept onto the pipes along the north side of the house on Gilpin Street in Denver, Colorado. The neighbors had not seen the Spangler family for four days. Newspapers piled up at the front door. The lights inside never changed.
Grace Mullen, who lived across the street and had been friends with Diane Spangler for six years, finally walked over and knocked. No answer. She tried the door handle. It opened.
What she found inside that home on December 17, 1978, would shape the next twenty-two years of Denver police investigations and the lives of the surviving relatives. But to understand what happened in that house, it is necessary first to understand the family who lived in it. Denver in 1978 was a city in the middle of a building boom, expanding toward the Front Range suburbs with speed and optimism. The streets of the Gilpin neighborhood were lined with large elm trees whose roots pushed up the sidewalk slabs every few years.
In December, the mountain cold swept down from the Rockies and settled into the neighborhoods like something permanent. The Spangler home was a two-story Victorian brick house that Robert and Diane Spangler had bought in 1968. It was the kind of house that required constant maintenance and rewarded the effort. They had painted it twice.
They had replaced the porch. Over ten years, they had made it their own. Robert Spangler was 43 years old in 1978. He worked as a news announcer for a Denver radio station, a job he had held for twelve years, giving him a warm familiarity with the part of the city that heard his voice every morning.
He was known for his smooth style, his physical fitness, running several miles a day, and for being, as his colleagues described him, a man who seemed entirely in control of his life. He and Diane had two children: Susan, 17, and David, 15. From every external angle, the family appeared stable, prosperous, and ordinary in the best sense of the word. Grace Mullen would later tell investigators that the last time she spoke with Diane was on Tuesday, December 12, 1978.
They talked over the fence about Christmas plans. Diane seemed completely herself. She mentioned that Robert would be taking a few days off during the holiday. She said she was looking forward to having him home.
That was their last conversation. On December 17, Grace opened the door of the Spangler home and found three people dead inside. Diane Spangler, Susan Spangler, and David Spangler. All three had died from gunshot wounds.
There was nothing else disturbed in the house. No sign of forced entry. No sign of a struggle. There was a note.
The note, found on the kitchen table in Robert Spangler’s handwriting, described what had happened as a family tragedy caused by his wife’s depression and her decision to shoot the children and herself. He wrote that he had been away from home when it happened. That he returned to find them in that condition. Then he drove to the mountains to process what he had been through.
Robert Spangler was found at a lodge in Durango two days later. He was fine and seemed composed. He told investigators the story in the note. He answered their questions fully.
He cooperated. The investigators were not convinced. The note raised immediate problems. The forensic evidence, the position of the three bodies, the trajectory of the bullets, and the absence of any gunpowder residue on Diane Spangler’s hands did not match the story the note told.
A detective named Larry Whetfield, 29 years old and four years into his work in the Denver homicide unit, spent three weeks examining the evidence and concluded that the crime scene was not consistent with a murder-suicide initiated by Diane. It was consistent with a man who killed his family and staged the scene to look otherwise. But there was no murder weapon. There were no witnesses.
And Robert Spangler had an explanation for every question Whetfield asked. The case was presented to the district attorney’s office. Prosecutors decided the evidence, although troubling, was insufficient to file charges. Robert Spangler was never arrested.
He left Denver shortly afterward. He moved to Arizona. He remarried within two years. He kept running.
He remained active and social. He never spoke publicly about the deaths of his family members. By 1985, seven years had passed. Detective Whetfield had been promoted twice, but he never closed the Spangler file in his mind.
He reviewed it every year or two, looking for something he might have missed. He found nothing new. The case remained open and inactive. By 1992, fourteen years had passed.
Robert Spangler had divorced his second wife in Arizona and married a third woman named Sharon Cooper. They moved to the Grand Canyon area, where Robert took up hiking seriously, the kind of hiking that took him into remote areas for days at a time. Sharon had health problems that made these trips difficult. She tried to keep up.
In April 1993, Sharon Spangler fell from a trail on the South Rim of the Grand Canyon. She died from the fall. Robert Spangler was with her. He told park rangers it was an accident.
The investigation was brief. The death was classified as accidental. The breakthrough did not come from forensic evidence. It came from a phone call Robert Spangler made himself.
In 1999, he was diagnosed with inoperable brain cancer. He was 64 years old. He was told he had a few months to live. Something happened inside him during those months.
The precise nature of that change is known only to him, but its result was a phone call to the FBI office in Denver in the spring of 2000. He asked to speak with an agent about unresolved cases. He was referred to Special Agent Alan Aulton, who handled the FBI’s Denver cold case and crimes against children unit. Aulton drove to meet Spangler at his home in Nevada, where Spangler was spending his final days.
During two recorded interviews, Robert Spangler confessed to three murders. He had killed Diane, Susan, and David Spangler on December 13, 1978. He had arranged the crime scene and written the note before leaving for Durango. He described the manner calmly, something Aulton later described as the most disturbing thing he had witnessed in 23 years of federal law enforcement.
He also confessed to the death of Sharon Cooper Spangler at the Grand Canyon in 1993. He had pushed her from the trail. He waited to make sure she could not call for help. Then he reported the incident as accidental.
He told Aulton he was telling him this because he had no other way to settle the account. He said he was not seeking forgiveness. He said simply that he could not die without confessing. Robert Spangler was arrested on April 4, 2000.
He was charged with first-degree murder in the death of Sharon Spangler, the only one of his four victims whose death occurred within the statute of limitations for available charges. He was indicted, tried in federal court, and sentenced to life in prison without the possibility of parole. He died in federal custody on August 5, 2001. He was 66 years old.
The Denver Police Department officially reclassified the deaths of Diane, Susan, and David Spangler as homicides in 2000 after Spangler’s confession. Their cases were closed. Not through the delivery of justice. The charges that would have addressed their murders had fallen under the statute of limitations.
Their cases closed with the truth. The official record now shows what actually happened in that house on Gilpin Street in December 1978. Diane Spangler was 40 years old. Susan was 17.
David was 15. They were killed by a man entrusted with their lives. Grace Mullen, who opened the front door that December morning, was in her eighties when Spangler’s confession became public. She said she had always known the note was false.
She knew Diane well. Diane would never have done that. She was right. It took 22 years and the decision of a dying man to confess what he had done.
Four people died because one man believed he could rewrite what happened and get away with it. He was almost right. But he ran out of time before the truth came out.