In the summer of 2020, in the small city of Florence, Colorado, a dispute between housemates would culminate in a fatal act of violence. On the evening of July 28th, 64-year-old John Achterkirch, a White male, was shot and killed in his own home. The events of that night were the tragic end to a period of escalating tension within the household.
Living with Achterkirch at the time were his niece, Danyelle Shatto, and her fiancé, 56-year-old Mark Nielsen.
The situation grew strained after another individual, Joleigha Johnson, moved into the residence and was subsequently arrested on an outstanding warrant. Achterkirch held Nielsen and Shatto responsible for Johnson's arrest and threatened to evict them from his home. This disagreement festered, creating a volatile environment.
On the night of the shooting, the conflict reached its breaking point. Nielsen would later claim to police that Achterkirch had physically assaulted him and had threatened to kill both him and Shatto. In the ensuing confrontation, Nielsen, who was armed with two handguns, fired a shot that struck Achterkirch in the face. When law enforcement arrived at the scene, they found Achterkirch on the floor with a gunshot wound. He was transported to a hospital but died from his injuries a few hours later.
Initially, Nielsen asserted that he had acted in self-defense. However, his account of the events began to shift as the investigation progressed. He attributed his inconsistent statements to being intoxicated and under the influence of marijuana at the time of the incident. Investigators also noted that Nielsen himself had sustained lacerations to his forehead and was taken into custody after being treated at a hospital. He was subsequently arrested on suspicion of second-degree murder. In March of 2022, following a trial, Mark Nielsen was found guilty of manslaughter in the death of John Achterkirch.
