Enrique Marquez Jr., a friend and former neighbor of San Bernardino, California, gunman Syed Rizwan Farook, was charged Thursday with buying the rifles used in the assault and plotting terrorist attacks with Farook in 2011 and 2012.
Investigators said Marquez, 24, bought the .223-caliber DPMS model AR-15 and Smith & Wesson M&P15 assault-style rifle used in the shootings Dec. 2 at the Inland Resource Center, which killed 14 people.
He was charged in U.S. District Court in Riverside, California, with conspiring with Farook to provide material support — including himself, a firearm and explosives — for crimes of terrorism; making a false statement in connection with acquisition of firearms; and immigration fraud for what authorities said was his sham marriage to a distant relative of Farook's.
Marquez was expected to make his initial court appearance later Thursday.
Officials told NBC News that Marquez has told them he bought the rifles as a favor so Farook wouldn't have to go through a background check or be on record as the buyer.
Marquez told the FBI that he and Farook talked about conducting some kind of attack in 2010 but called it off after unrelated terrorism arrests in Southern California, authorities told NBC News.
Marquez checked himself into a mental hospital for a few days after the shootings. Farook and his wife, Tashfeen Malik, who were killed in a shootout with authorities a few hours after the massacre, were quietly buried Tuesday in Southern California.
This story originally appeared on NBCNews.com