A decades-old Colorado cold case might just one step closer to being solved. Between the years of 1965 to 2023, approximately 345,000 cases of homicide and "non-negligent manslaughter" went unsolved, according to the official Project Cold Case website. In 2003, a 29-year-old from Colorado named Rosa Arguello was found dead from multiple stab wounds in Thornton, according to CBS reports. Read More: Body Found in Horsetooth Reservoir SearchBreak in the Thornton Murder Case: Suspect Arrested After 22 Years In IowaFor nearly 22 years, her case ran cold. However, a possible suspect in this murder case was arrested hundreds of miles away in the Midwest.