(NewsNation) — New details from the Oct. 24 St. Louis school shooting have emerged, indicating that one week before the incident, police had taken away the AR-15-style rifle the suspected gunman used to kill a teacher and a 15-year-old girl.

The alleged shooter was killed in a shootout with police at the school.

The information was released during a Wednesday news conference, at which interim St. Louis Metropolitan Police Chief Michael Sack said officials helped the suspect’s family transfer the weapon out of his hand.  

“What they did is they contacted us and said that he had a firearm,” Sack said. “It could’ve possibly been this gun.”

Officers handed over the weapon to an adult who was lawfully able to possess it, Sack said.

“The mother at the time wanted it out of the house, so they facilitated that. … This other party had it,” he said. “How (the suspect) acquired it after that, we don’t know. That’s what we’re looking into.”

Also on Wednesday, KMOV reported that police confirmed the weapon obtained was, in fact, the same one used at Central Visual and Performing Arts High School and Collegiate School of Medicine and Bioscience.

In addition, KMOV obtained police reports showing that officers went into the shooter’s house to check on a “domestic disturbance” days before the shooting, and at least six times overall, for issues that included a suicide attempt, a weapon-related issue, and a call for a crisis response unit.

“Mental health is a terrible thing, and we can’t anticipate what will come, but that family appears to have done everything they could’ve possibly done to try to help this young man live with his mental health issues,” Sack said at the news conference.

Local authorities are reportedly working with the Bureau of Alcohol, Tobacco, Firearms and Explosives, and have shared the serial number on the weapon in hopes of tracing it from the manufacturer to the original seller of the weapon.

So far, investigators have discovered that the suspect attempted to buy a gun from a licensed dealer in St. Charles but was blocked by an FBI background check. The suspect then reportedly purchased the weapon through a private seller.

“The suspect sought out and bought the rifle used in the school shooting from a private seller, who legally purchased the weapon from a federally licensed dealer in December 2020,” SLMPD Sgt. Charles Wall told KMOV in an email.

“There is no existing law which would have prevented the private sale between the original purchaser and the suspect in this case,” he continued. “The State of Missouri does not have a red flag law. That means SLMPD officers did not have clear authority to temporarily seize the rifle when they responded to the suspect’s home when called by the suspect’s mother on 10/15/22.”