01/13/2012 08:34 am ET Updated Dec 06, 2017

Michael Clark Is Charged With First-Degree Murder In 1994 Cold Case

A man has been arrested and formally charged with murder in the first degree in the 1994 killing of Marty Grisham.

While having dinner in his Boulder apartment with his girlfriend on Nov. 1, 1994, 48-year-old Grisham -- the city's director of data processing -- answered a knock at the door. His girlfriend would later tell police that she believed Grisham gave her a look that said he was surprised at the identity of the knocker, just before he was shot four times in the head and chest. She couldn't see who shot Grisham, and there were no other witnesses.

But Michael Clark, now 36-years-old, was always considered a suspect in the case according to Boulder Police spokeswoman Kim Kobel. Clark was friends with Grisham's daughter at the time of the killing and had stolen a box of checks from Grisham's house using the key she had lent him to take care of her father's cat.

Clark initially emerged as a suspect in the case in large part because Grisham had identified him as a suspect in the $4,500 check forgery earlier on the same day he was killed. The recently unsealed arrest affidavit shows that while he was in Boulder County Jail on the forgery charges, a cellmate of Clark's says that Clark confessed to killing Grisham.

Just weeks before the murder, Clark obtained a 9mm gun and detectives say that Clark's story contains inconsistencies after being reinterviewed last summer about that gun.

CBS4 says that having a new detective on the cold case may have lent a very valuable set of fresh eyes to lead to an arrest, and that investigators believe Clark used someone else to buy the gun from a pawn shop. The gun has never been recovered.

Boulder Police Chief Mark Beckner however told the Daily Camera that no new DNA or forensics were responsible for the arrest in this cold case, just "good, old-fashioned detective work."

This will be the sixth cold case to lead to charges since 2009, when Boulder District Attorney Stan Garnett took office.

Photo of Michael Martin Clark, suspect charged in the first-degree murder of Marty Grisham: