One of the guns seized by law enforcement in the home where Shannon Gooden shot and killed two Burnsville police officers and a firefighter-paramedic was bought illegally in what is called a "straw purchase," according to the owner of the gun shop where the weapon was obtained weeks before the shooting.

John McConkey told the Star Tribune that an AR-15 lower receiver was picked up by the purchaser at the Modern Sportsman Gun Shop and Range in Burnsville, roughly 6 miles from where Gooden unleashed more than 100 rounds of gunfire during an hourslong standoff on Feb. 18 in the 12600 block of S. 33rd Avenue.

The lower receiver generally contains the assault-style rifle's serial number and is the central part to which the firearm's other components attach to make the weapon function. In September, the State Supreme Court ruled that defendants can be convicted of a felony if caught with disassembled or incomplete gun parts.

Gooden, 38, lost his right to possess a firearm after his conviction in 2008 for second-degree assault in Dakota County. In August 2020, Gooden petitioned the court unsuccessfully to regain his right to a gun. He said that he wanted to protect himself and his family, according to court records.

McConkey added Tuesday that he does not know whether that weapon, among multiple firearms found in Gooden's home, was fired during the standoff or mortally wounded any of his victims, officers Paul Elmstrand and Matthew Ruge, 27, and firefighter-paramedic Adam Finseth, 40. Gooden then fatally shot himself while seven children were in the home.

The lower receiver "was purchased from an out of state online retailer and shipped to our shop for transfer" to the buyer, McConkey said. "The purchaser passed the [FBI] background check and took possession of the firearm on January 15th."

McConkey emphasized that his gun shop "had no way of knowing the lower receiver would end up in a convicted felon's/prohibited person's possession. [Gooden] was not there during the transfer process, nor was his name on any of the enclosed documents."

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives recently raised concerns about guns being stolen across the country from lawful owners, manufacturers or licensed dealers.

People who are prohibited from purchasing firearms — those with felony or misdemeanor domestic violence convictions, involuntary mental illness commitments and illicit substance abuse — sometimes turn to legal buyers with clean criminal histories to buy weapons on their behalf, known as "straw purchasing."

The person who picked up the firearm is "under investigation for committing a felony straw purchase," McConkey said. "We are working closely with the BCA [Bureau of Criminal Apprehension] and cannot release any more information at this time due to this being an ongoing investigation."

BCA spokeswoman Bonney Bowman declined Tuesday to confirm McConkey's account, saying, "Due to the active nature of the investigation, I'm not able to share any additional details at this time."

The BCA's investigators seized several firearms and a large amount of ammunition at the scene of the shootings. They also recovered cartridge casings that showed Gooden had fired "more than 100 rifle rounds at law enforcement and first responders," the agency said last week. The BCA has yet to disclose how Gooden came to illegally possess the guns and ammunition.

The deadly standoff began after police were called about "an alleged sexual assault allegation," according to a search warrant affidavit filed last week by the BCA, which has not offered a possible motive for the gunfire.

A memorial service for Elmstrand, Ruge and Finseth is scheduled for 11 a.m. Wednesday in Eden Prairie in Grace Church's 4,300-seat auditorium. The service can also be watched on a livestream. Afterward, a procession for the three first responders will make its way from the church to Burnsville. The public is invited to line the route to show support for the fallen, city officials said.

Star Tribune staff writer Stephen Montemayor contributed to this report.