Enrique Marquez, a neighbor and friend of one of the San Bernardino shooters, has been arrested for allegedly providing material support to terrorists, officials said.
Authorities said that Marquez and shooter Syed Farook allegedly began plotting terror attacks in Southern California in 2011 -- "attacks which were, fortunately, not carried out -- and discussed a firearms and explosives attack on Riverside Community College.
"While there currently is no evidence that Mr. Marquez participated in the Dec. 2, 2015 attack or had advance knowledge of it, his prior purchase of the firearms and ongoing failure to warn authorities about Farook's intent to commit mass murder had fatal consequences," said U.S. Attorney Eileen M. Decker of the Central District of California.
During a court appearance Thursday, Marquez said that he understood the charges against him. His lawyer did not immediately comment and he did not enter a plea. Marquez is scheduled for a bail hearing at 2 p.m. Monday, and will be held until then at the Metropolitan Detention Center in downtown Los Angeles, Public Affairs Specialist Laura Eimiller of the FBI told ABC News.
Farook's attack on the Inland Regional Center, committed along with his wife Tashfeen Malik, left 14 people dead and another 22 injured. The FBI was investigating the incident as an act of terrorism.
According to authorities, Marquez illegally purchased the two "assault rifles" that were used in the massacre along with a pair of hand guns. He also allegedly bought smokeless powder to make explosives in 2012 and went to firing ranges in Riverside and Los Angeles to practice.
Contact between the two men declined in 2013 and they ceased planning attacks, Marquez allegedly told authorities.
The earlier planned attacks, which the men never ended up carrying out, were allegedly going to be centered around either a library or cafeteria at the Riverside Community College, which both Marquez and Farook attended, and specific lanes of a major highway during rush hour, the Department of Justice said today.
"The plan was for Farook to throw pipe bombs on to the freeway, which they believed would disable vehicles and stop traffic," authorities said in their release. "Farook allegedly planned to then move among stopped vehicles, shooting into them, while Marquez shot into vehicles from a position on a nearby hillside. Marquez allegedly said that he would watch for law enforcement and emergency vehicles, and his priority was to shoot law enforcement before shooting life-saving personnel."
Officials also accused him of "defrauding immigration authorities by entering into a sham marriage with a member of Farook's family." The marriage in question was Marquez's marriage to "a member of Farook's extended family so that she could obtain legal status in the United States," the Department of Justice press release stated. In return for agreeing to the marriage, Marquez was paid $200 per month.
Officials have said they believe one of the San Bernardino gunmen, Syed Rizwan Farook, asked Marquez to buy the two "assault-style" rifles back in late 2011 or early 2012.
In a Facebook posting from Marquez's profile just hours after the attack, he said, "I'm. Very sorry sguys. It was a pleasure."[sic]
The FBI has questioned Marquez and he has provided the agency with information not previously known, federal officials said earlier this month.
"He's continued to cooperate with investigators since they got ahold of him," a counter terrorism official familiar with the investigation told ABC News.
Farook and Malik were killed in a shootout with police shortly after the initial attack at the Inland Regional Center.
Marquez's mother and brothers declined earlier this month to discuss the investigation, but friends of Marquez told ABC News he is a "great guy." Viviana Ramirez, who went to school with Marquez, said she thought it was a joke when she heard his name linked to the San Bernardino tragedy.
ABC News' Jack Date and Pierre Thomas contributed to this report.