DENVER — The U.S. Department of Justice Inspector said he will run an audit to figure out how a Columbine-obsessed 18-year-old from Florida was able to purchase a shotgun in Colorado just hours after arriving in the state.

This comes after U.S. Rep. Joe Neguse (D), from Lafayette, had requested an FBI investigation into the April 2019 incident involving Sol Pais that prompted a massive manhunt and the closure of hundreds of schools across the Front Range.

The Colorado gun shop that sold Pais the shotgun stated that she passed the required criminal background check, but a review of federal law shows the transaction should not have been allowed to take place, according to a news release from Neguse’s office.

Federal code states a sale of a firearm is legal "provided the transaction complies with state law in the state where the licensee is located and in the state where the purchaser resides."

In this case, Pais could legally purchase a shotgun at 18 under Colorado law, but she would have to be 21 to buy the same gun in Florida.

The federal investigation will look into information on how Pais was able to buy a gun in an effort to prevent similar situations going forward.

Pais died of a self-inflicted gunshot wound near Echo Lake in Clear Creek County, likely on the afternoon or evening of April 15. Her body was not discovered until April 17.

“We must ensure that our state’s background checks are as effective as they can be and that the proper steps are taken to prevent this from happening again," Neguse said. “While the DOJ Inspector General's acknowledgement of these issues is a positive development, I implore the Inspector General to provide Congress with a clear and expedited timeline for their audit of the Point of Contact system, and to provide answers on how this incident was able to occur.”

Neguse serves on the House Judiciary Committee, which provides oversight of the Department of Justice (DOJ). 

RELATED: No drugs, alcohol in system of Florida woman whose trip to Colorado sparked widespread school closures

RELATED: FBI says investigation will continue after Florida woman suspected in school threats found dead

RELATED: Florida woman purchased gun from Jefferson County store; Here's what it takes to buy a gun in Colorado

RELATED: 500,000 Colorado students back in class after alleged threats shut down Denver area schools

SUGGESTED VIDEOS: Local stories from 9NEWS