AUSTIN (KXAN) — A man suspected in an explosion in an Austin hospital parking garage that occurred in August entered a guilty plea on Monday, the U.S. Department of Justice said in a news release.

Raymond Luke Garner, 38, of Jonestown, pleaded guilty to possessing an unregistered destructive device, which officials referred to as a pipe bomb, that detonated in a parking garage at St. David’s Medical Center, the release said.

On. Aug. 9, Garner parked his pickup truck in the parking garage, and shortly after, there was an explosion in the back of his pickup, according to officials. Law enforcement investigators found the remains of a pipe bomb near Garner’s pickup. They also found homemade high explosives, circuit boards and timers, electric matches as well as other items, the release said.

Image of Raymond Luke Garner

An agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives, or ATF, conducted the report and said Garner, shortly after being detained for questioning, sent a message to an individual saying, “I need you to please go to my house and take the box in front of my washer home. It’s very important that you do this as soon as possible.” He also stated, “I’ll explain later.”

The affidavit said the individual retrieved a box from Garner’s residence the same day as the explosion at the hospital and later brought the box into their apartment.

The box was later found to contain a quantity of the high explosive, precursor chemicals and electric matches, the release said. Searches at other locations revealed a recipe for the high explosive, remote control devices, as well as other components for destructive devices. Garner admitted he was in possession of an unregistered destructive device on Aug. 9, according to officials.

Garner faces a maximum sentence of 10 years in prison, the release said.