Michael Kiser Addison was born in Boston on March 19, 1980. At the age of two, he was adopted by his maternal grandmother, Rosetta Addison, and her husband, Lucious Addison. Lucious was a disabled Vietnam veteran. After a while, Lucious and Rosetta divorced. Rosetta took care of her teenage children and Michael in a home described as chaotic.

As a child, Michael spent time living with his grandmother in Brockton, Massachusetts. He also experienced life with his mother, who struggled with alcoholism. This part of his life occurred in one of Boston's most violent and drug-ridden housing projects located in the Roxbury neighborhood.

Michael attended high school in Dorchester but did not graduate. His early life was filled with challenges due to his complicated family background. This troubled upbringing was later presented during his trial as an explanation for his actions.

At the time of the incident involving police officer Michael Briggs, Addison was living in Manchester, New Hampshire. He had encounters with law enforcement, including an arrest by Officer Briggs in 2002 near the Queen City Bridge in Manchester. In March 2003, Briggs provided Addison with first aid after he was shot in a separate incident.

Addison faced numerous legal issues throughout his early life. In October 2003, he was arrested in Londonderry, New Hampshire, on several charges, including false imprisonment and criminal threatening. He pleaded guilty to one charge and served a sentence of six months. He acknowledged violating probation during this time.

On October 16, 2006, Officer Michael Briggs was shot while responding to a domestic disturbance call in Manchester, New Hampshire. He and his partner, Officer John Breckenridge, confronted Michael "Stix" Addison and his accomplice, Antoine Bell-Rodgers. When ordered to stop, Bell-Rodgers complied, but Addison fled and shot Briggs instead. The officers returned fire, but Addison escaped the scene.

After the shooting, police initiated a manhunt for Addison. They searched the area, including the apartment of Addison's girlfriend, where they found blood-stained clothing. Addison managed to evade capture for around fifteen hours before being arrested in Dorchester, Massachusetts, after being located by the Boston Police Department. He was charged with being a fugitive and extradited back to New Hampshire.

In New Hampshire, Addison faced multiple charges, including capital murder for killing a police officer. The prosecution sought the death penalty, which led to discussions about capital punishment in the state. Following the events of the murder, evidence pointed to a string of crimes committed by Addison and Bell-Rodgers over the prior week.

Addison was eventually tried for capital murder in September 2008. During the trial, he admitted to shooting Officer Briggs but claimed it was not intentional. The jury found him guilty and sentenced him to death. On December 18, 2008, Addison received a death sentence, making him the only person on death row in New Hampshire. This decision was upheld by the New Hampshire Supreme Court and later, the U.S. Supreme Court declined to hear his appeal.

Addison's legal battles regarding his conviction and sentence continued for several years, but the courts maintained his conviction and sentence.