There's a long list of unsolved crimes in Colorado, many of which have baffled authorities for years.

Colorado is one of those places everyone loves, and for good reason. I mean, it’s awesome here – we’ve got those amazing mountains, great people, and a ton of history and culture, plus a never-ending list of things to do. 

Despite all of the positives, Colorado does have a dark side and has been known for some darker reasons, as the state carries its fair share of crime. Home to the Administrative Maximum Penitentiary, or ‘Super Max,' in Florence that houses some of the worst criminals in the country’s history – and is now home to El Chapo.

Many of these crimes have never been solved, and in some cases, decades have passed. The state has a rather sordid history of serial killers and notorious criminals, along with instances of gun violence and shootings in recent years. The Colorado Bureau of Investigation (CBI) and local police departments continue to try and solve these cases, vowing to never forget or give up on bringing those responsible to justice, and giving closure to the families and victims.

We did some research and are presenting you with the stories behind five of Colorado’s most notorious unsolved crimes.

Shelly Robertson

Courtesy of Remembering Victims of Ted Bundy (Facebook)

Shelly Robertson grew up in Arvada, Colorado, and graduated from Arvada High School in 1969. Growing up, Shelly held fast to the idea that one day a white horse would walk into her life and that she would name him Brownie. Her mother knew the story well, and one day, the girl’s prediction came true, though it was a neighbor’s horse. The interaction led to this neighbor helping Shelly get her own horse, a little gray mare named "Bonnie," which the girl rode bareback throughout her childhood. Shelly was an active member of the Church of Christ and spent a year after high school on a mission trip in Biloxi, Mississippi. She studied Spanish at the Red Rocks Community College and spent a semester in Mexico with her class, and went on to spend time in Alaska as well. Shelly was a pretty girl, full of life, enjoying the freedoms that came with living in Colorado in the 1960s and ’70s.

In late June 1975, Shelly disappeared and was never seen or heard from alive again. She went missing on June 29, 1975. Twenty-four days later, her lifeless, naked body was found dumped in the WIllie May Mine, located one mile east of Berthoud Falls, Colorado. Due to the state of the body, there was no way that authorities could pinpoint a cause of death.

It has been reported Shelly had a fight with her boyfriend the day she disappeared, got out of the car and hitched a ride home. Sadly, she never made it home, and the theory that many accept as her fate is that she came into the clutches of one of the vilest and evil men in history.

Serial killer Bundy was interviewed in Salt Lake City, Utah, sometime later, and was asked about Shelly. Bundy would only say that he would not discuss the girl. A receipt from a Golden, Colorado, gas station dated just days before her disappearance was found under the seat of his car, and witnesses mentioned seeing Shelly in a beat-up old truck with a man around the time she went missing.

Her case has never been solved, however, it has been reported that Bundy confessed to her murder before his execution. While the case has never been officially closed, it is the belief of authorities and her family that Shelly was a victim of Bundy. Though the man was executed for his crimes, he was never charged with killing Shelly.

Mile High Hammer Murders – Bennett Family

Courtesy of Pixabay

In 1984, Vanessa Bennett was a three-year-old child who had just moved with her mom, dad, and older sister to a new home in Aurora, Colorado. On the morning of January 16, 1984, Vanessa’s grandmother came to check on the family after her son and his wife didn't come into work. What she found was a scene from a horror movie.

All four members of the family had been savagely attacked, beaten brutally with a hammer. Vanessa’s father lay crumpled at the bottom of the stairs, his throat slashed with a butcher knife as he fought for his life. Vanessa was the only one left alive and she suffered life-threatening wounds and barely clung to life. She was in a coma with her jaw wired shut, fed through tubes, and had years of therapy and recovery to face from that night’s events.

Her entire family had been killed that night, and for 34 years, the killer would go unnamed, leaving the horrific attack on the Bennett family one of the most brutal unsolved crimes in Colorado history.

In August of 2018, Vanessa Bennett, who now lives in Arizona, received a call that would change her life, again. A prisoner in Nevada, Alex Christopher Ewing, 58, had come up as a match to DNA found at the crime scene. DNA from cold cases in Colorado are run through the national database for comparison, and they'd found a match. Ewing was serving time for beating a young couple in Nevada with an ax handle and was matched to both the Bennett murders and another unsolved attack in Lakewood, in which Patricia Louise Smith was beaten, raped, and killed with a hammer just days before the attack on Vanessa’s family. Ewing faces murder and sexual assault charges in both cases and is currently fighting extradition to Colorado.

Vanessa has moved on with her life as best she can, but the fractured skull, jaw, and pelvis she suffered at the hands of her attacker have left her with lifelong health, emotional, and mental issues, and at times, she has lived on the streets. We wish her well and hope that she finds peace in this life for what was done to her and her family.

Karen Lynn Pineda Nelson

On December 9, 1989, two farmers working in Morgan County saw a fire burning in another farmer's field and went to investigate and possibly help. Instead of finding a brush fire, they found a horrific sight; a woman’s body was burning, and she had been decapitated and dismembered, her hands cut off. 

Colorado had just begun using forensic science to identify human remains, and though the killer had attempted to hide the woman’s identity, they were no match for science and Karen Lynn Pineda Nelson was identified as the victim of this unspeakable cruelty. In a sad milestone, she was the first Jane Doe the state was able to identify using DNA matching, despite the killer’s grotesque attempt to prevent the victim from being identified. 

Karen Lynn Pineda Nelson was a woman with a troubled soul, known to struggle with addictions to alcohol and drugs. She had spent time living on the street but never went more than a week or so without contacting her family, according to her sister, Debra Trujillo. So when the family spoke to her on the day before her 29th birthday, November 28, 1998, they did not expect it to be the last time they would have contact.

Several weeks had passed, and Debra grew more and more concerned. Her sister was troubled, but this behavior was out of character for her. Debra contacted authorities and was shocked to find out that Karen’s husband, Charles Ray Nelson, had filed a missing person’s report one month prior in Arapahoe County, though he had not shared that with her family. He claimed Karen had drugs on her person the night of her birthday and that they had a terrible argument. He insisted that Karen had taken off with another man and headed to Florida. He claimed he had waited the two months to report her missing due to her habit of taking off for weeks by herself. Charles went as far as to claim he knew she was alive because he had friends in Florida who told him where she worked and had reported seeing her there. 

The Jane Doe report from Morgan County was seen by investigators in Arapahoe County, and the remains were tested, confirming that the mutilated woman was, in fact, Karen. 

All evidence, then and now, pointed to Charles Nelson and police were never able to confirm his version of the last time he saw his wife alive. He was, and still is, considered the prime suspect by all parties, including authorities in her death, though he has never been charged and the case remains unsolved. Karen’s family no longer questions what happened to her, though they may never get justice for her death.

William E “Billy” Trimbach

Courtesy Morgan County Sherrif's Office (Facebook)

Billy Trimbach was a proud father to an infant daughter, a stepfather to a nine-year-old boy, and a loving husband to his wife, Cindy, as well as a doting dad to his two children from a former relationship. The couple had been married on Valentine’s Day 1992 in Stoneham, Colorado. One year later, on their first wedding anniversary, Billy was found shot to death on the side of the road in Morgan County. His body was 50 miles from his home and he had been shot multiple times with his own nine-millimeter handgun.

Cindy Trimbach had called the police the morning of February 14, 1993, reporting that she had not seen or heard from her husband since the previous morning. Her nine-year-old son told police he had seen Billy leave that morning with an unknown man needing help with his car. Billy was a mechanic, so this seemed to make sense. When the body was found, investigators determined Billy had not died at the scene, that he had been killed elsewhere and his body had been dragged to a car, then dumped by the roadway.

Cindy began to behave in a way that made investigators question her motives, discovering she had taken out a $500,000 life insurance policy on Billy days before his death and forged his signature. She made a comment about driving right by where Billy's body had been found near Wiggins the night before as she searched for him. The Sheriff had also been driving by that night and remembered seeing multiple cars in the same spot, leading him to believe he had actually unknowingly witnessed Billy’s body being dumped. 

Cindy suffered from AIDS, having contracted it with her former husband, and Billy had worked extra shifts to pay for her medical care and alternative treatments. The insurance money would have been very helpful in her treatments, and investigators began to find other clues leading them to believe Cindy was not the grieving widow she claimed to be. They found blood in the back of her car that matched Billy's and items recovered near the body matched those she had been known to carry in her car. 

Shortly after she buried her husband, Cindy took her son and moved to Butte, Montana. It is unknown what happened to the infant daughter she shared with Billy. In Montana, her son was bullied at school due to his mother’s AIDS, and Cindy told his school there that her son was traumatized after seeing his stepfather murdered in front of him. This was not the same story she told in Colorado, and the story did not help her son. The bullying intensified and the boy made a deadly decision of his own; taking his mother’s gun to school he opened fire, shooting and killing an 11-year old classmate with a shot to the head. 

When investigators talked to the boy, he recanted his story about seeing Billy leave with a man the day before his death and told police that he had made the story up to cover for his mom, who he believed was responsible for killing his stepfather. Beyond that, the boy would give no further details, and Cindy succumbed to the AIDS virus in 1994, a year after Billy was found dead. 

In 1998, Cindy’s former drug dealer committed suicide after police contacted him about his involvement in the murder, claiming he was the only person left who could be prosecuted for the death of Billy Trimbach. No other suspects have been identified and no one was ever charged with the murder. The common belief is that Cindy took out a hit on her husband to collect his insurance money. The case remains unsolved and there may yet be a killer lurking in Colorado, but only Billy and the murderer themselves know the truth.

The Morgan County Sheriff is still hoping to find justice for Billy and his orphaned children, so anyone with information is asked to contact the Sheriff's office there.

Alfred Beilhartz

Courtesy of Cold Cases (Facebook)

This case goes all the way back to 1938, the oldest on our list. The young child was on vacation with family in Estes Park when he disappeared. Alfred, a five-year-old boy, was fishing and playing in the area between the Roaring and Fall Rivers. After a day of fishing and bathing, the family returned to camp only to realize that Alfred had gone missing. The authorities were called in and a huge search began, with his scent being tracked 500 feet uphill from where he was last seen.

The day after he disappeared, a couple hiking further up in the park near Devil’s Nest reported seeing the young child sitting alone and hearing his cries, however, after a 10-day search with bloodhounds and over 150 men looking, there was no sign of the child. Alfred is recorded as the first drowning ever to be recorded in Rocky Mountain National Park, though with the body never being found, some wonder if that was actually his fate.

There have been other reported sightings of Alfred over the years, one claiming the boy was seen with a man in Nebraska, a ransom note for $500 was sent to his parents a few months after he disappeared and a bandage found in an abandoned cabin was tested for a possible match. Alfred was never found, and his father held onto the belief that Alfred was abducted for the rest of his life, though that has never been proven. No one can say for sure what happened all those years ago, and due to the amount of time that has passed, the case is no longer being investigated. Maybe one day the world will know what happened to the young boy, we just hope wherever Alfred went, he is at peace and did not suffer any pain.

Colorado has a long list of unsolved crimes and disappearances, many of which still get tips even though many years have passed. Every once in a while, one of these tips leads to closure, something that the victims and their families seek and need.

What do you think about Colorado’s number of unsolved crimes? Have you heard a story about one of the cases we presented? Let us know your thoughts and any other unsolved crimes we should look into in the comments below.