Updated

The next-door neighbor of San Bernardino shooter Syed Farook, who allegedly helped him build his arsenal, may have been involved himself in an attack plot cut short three years ago.

According to senior American officials cited by The New York Times, Enrique Marquez not only purchased the two assault rifles used in last week’s massacre, but was an Islam convert who had discussed plans to carry on an attack as far back as 2012.

Authorities say Marquez, who checked himself into a mental health facility two days following the attack, legally bought two AR-15 assault rifles that were used by him and his wife Tashfeen Malik to kill 14 people and wound 21 others during a holiday party on Dec. 2 in San Bernardino's Inland Regional Center.

Marquez has been cooperating with FBI investigators and providing significant information about the couple, the Times said.

ABC News is reporting that he could now face criminal charges for the purchases, made in 2011 or early 2012.

The 24-year-old is also connected to the shooters by marriage. According to Reuters, Marquez is married to Mariya Chernykh, whose sister is the wife of Raheel Farook, the brother of Syed.

Besides his marital ties, Marquez converted to Islam about five years ago and attended the Islamic Society of Corona-Norco before practicing at another mosque, according to the New York Times.

As time went on, Marquez started attending mosque less and less frequently, the facilities manager told the Times he hadn’t seen Marquez in about three years.

In an interview with ABC News, a friend of Marquez, Michael G. Stone, said he made a statement months ago that may indicate he knew about the couple's plans.

“He said something along the lines of, ‘There’s a lot of Muslims in our own backyard, just ready to go haywire and attack,” Stone told ABC News. “And we didn’t think nothing of it. We just brushed it aside, you know. He was drunk, so I don’t know.”

Marquez’s stepfather recently told the New York Times he was stunned by the claim that his stepson had purchased weapons for the couple.

“I have no idea,” he said. “It is so strange to us. We don’t have anything to do with guns.”

Like us on Facebook
Follow us on Twitter & Instagram