DENVER (KDVR) — There are hundreds of unsolved homicide cases, long-term missing person cases, and unidentified remains cases in Colorado where at least three years have passed since the crime happened.

The Colorado cold case task force created a list of those cases dating back to 1970. The Problem Solvers are working to highlight cold cases in our state.

Who murdered Marcus Mason?

The Colorado Bureau of Investigation and Denver Police Department are working to solve the cold case murder of Marcus Mason.

Police said it happened on July 22, 2007 around 10 p.m.

Mason and a friend were walking in a neighborhood near Olive Street and 35th Avenue when they were approached by a group of unknown men. Police said that one of the men shot Mason and then left the area.

Mason was pronounced dead. He was 17 years old at the time of his death. To this day, his case remains unsolved.

No suspect information has been released.

If you have any information about Mason’s murder, please contact the Denver Police Department at 720-913-2000.

You can also reach out to Metro Denver Crime Stoppers and remain anonymous by calling 720-913-7867.

Highlighting cold cases in Colorado

Here are some of the other cases we’ve highlighted:

If you ever have a cold case you would like us to feature, please fill out this form or send an email to dara.bitler@kdvr.com-

The National Missing and Unidentified Persons System shows there are currently 21,556 open missing persons cases in the United States and over 300 in Colorado.