The former neighbor of the couple who carried out the massacre in San Bernardino, California, was indicted on Wednesday on charges of conspiring to provide material support to terrorists, Reuters reports.
Prosecutors say Enrique Marquez, 24, supplied assault rifles to the couple. Marquez was charged with conspiring with gunman Syed Farook in 2011 and 2012 to support a terrorist attack that was never carried out.
Farook and his wife, Tashfeen Malik, stormed into a holiday party attended by his co-workers at a San Bernardino County social services agency and opened fire on December 2, killing 14 people and wounding 22 others.
Farook and his wife, who had a baby daughter, were killed in a gun battle with police following the shooting, which is being investigated as a terrorist attack.
The FBI has said that Farook and Malik were both radicalized "for quite some time" and had taken target practice at Los Angeles-area shooting ranges, and once "within days" of the massacre.
Marquez, who was arrested earlier this month, was also accused in the indictment, which was handed down in U.S. District Court in Los Angeles, of lying to federal authorities about the purchase of two assault rifles that were used by Farook and his wife in the San Bernardino shooting rampage.
Marquez is also charged with entering into a sham marriage with a Russian woman in Farook's extended family so that she could live in the United States, according to Reuters.
The indictment supersedes a criminal complaint containing similar charges that was filed against Marquez earlier this month and allows prosecutors to proceed to trial without holding a lengthy evidentiary hearing first.
Marquez is being held without bail on those charges.
Prosecutors say Farook and Marquez met in 2004 when they became neighbors in Riverside, California and that Farook introduced the younger man to radical Islamic theology.
According to an FBI affidavit, Farook and Marquez were plotting gun and bomb attacks as early as 2011, but never carried them out before their friendship waned, according to Reuters.
Prosecutors have said, however, there is no evidence that Marquez had direct prior knowledge of the December 2 attack in San Bernardino.
It is believed Farook had contact with people from at least two terrorist organizations overseas, and investigators have also said Malik had pledged allegiance to the Islamic State (ISIS) group in a Facebook posting.