The felon accused of fatally shooting another man in a Longmont Walmart parking lot — an act prosecutors ruled was self-defense — also will not face charges related to the possession of a firearm by a previous offender.

While Joseph Anderson was released from custody Tuesday after prosecutors declined to press charges, Longmont police have not closed their case and continue to investigate — though they are vague as to why.

“We are working many different angles of this investigation,” Sgt. Matt Cage said Wednesday.

Weld County District Attorney Michael Rourke announced Tuesday that Anderson, 34, was acting in self-defense on July 23 when he shot 33-year-old Keith Williams, who reportedly approached him with a 16-inch-long club-like tool.

Rourke deemed Anderson’s possession of the gun used in the shooting to be legal based on the Colorado Supreme Court’s 2012 ruling in People vs. Carbajal, which established that a previously convicted felon can possess a weapon for the purpose of defending his home, property or person, spokesman Tyler Hill said.

“We would have to disprove self-defense, which, in this case, the evidence gathered by the Longmont Police Department points to self-defense,” Hill said.

Felons are flagged in background checks when purchasing firearms, though Hill said prosecutors don’t know when Anderson obtained the gun.

“It doesn’t matter if it was still used in self-defense,” Hill said, adding that the DA’s office has been receiving calls from people asking for clarification about why Anderson wasn’t charged with possessing a firearm.

Anderson, of Northglenn, was convicted in Jefferson County of felony dangerous drugs charges in 2005 and 2009, and sentenced to prison for five years and six years, respectively, according to police records. He also has been arrested for failing to appear in court, disorderly conduct, violating a restraining order, failure to pay and failure to comply as well as parole violations, records show.

According to an arrest warrant affidavit released Tuesday, Anderson sped away from the scene of the shooting. His vehicle was recovered in Westminster later that afternoon and he was arrested in Loveland on July 26 on suspicion of second-degree murder.

Hill said it was not illegal for Anderson to leave the scene of the shooting, which is different than the law making it illegal to flee the scene of a traffic crash.

“There is no law that addresses leaving the scene of a shooting or crime, so there’s nothing we could charge him with in that regard,” he said.

Anderson and Williams had not met prior to the shooting around 3 a.m. July 23. They were both expecting to meet up with Shanna Cathey, according to the affidavit.

Hill said none of the evidence pointed to the meet-up being a drug deal, though Williams was found with heroin and methamphetamine in his possession. It is unknown whether Anderson had drugs on him at the time because he immediately left the scene.

Cage, of the Longmont Police Department, said, “We have the same information as the DA and all aspects are being investigated.”

Amelia Arvesen: 303-684-5212, arvesena@times-call.com or twitter.com/ameliaarvesen