The California man accused of arming the couple who carried out the San Bernardio massacre pleaded not guilty Wednesday to federal terror charges.
Enrique Marquez Jr. entered pleas to accusations including conspiring to provide material support to terrorists, lying about weapons purchases, marriage fraud and lying on a visa application.
He was indicted last week by a federal grand jury.
He did not participate in the Dec. 2 attack by Syed Rizwan Farook and wife Tashfeen Malik, but prosecutors say he plotted with Farook to attack a nearby community college and a major freeway that connects the area to Los Angeles.
The 24-year-old Marquez, clad in a white prison jumpsuit and shackled at his waist and feet, made a brief appearance in a federal Riverside court.
He said little, replying only "yes" or "no" to questions posed by Magistrate Judge Sheri Pym, the Los Angeles Times reported.
According to prosecutors, Marquez purchased two high-power rifles in 2011 and 2012 and gave them to Farook.
He was the couple's neighbor at the time.
He lied when buying the rifles, saying they were for his use, authorities said.
Prosecutors have also said Marquez called 911 when he saw live news broadcasts from the carnage at the Inland Regional Center in San Bernardino. He told the dispatcher that he knew the shooters and that they were using his weapons, which were stored at the couple's house, authorities said.
Fourteen people were killed and 22 were injured when the couple barged into a holiday party attended by Farook's co-workers. The husband and wife later died in a shootout with law enforcement officers, leaving behind a six-month-old daughter.
Marquez entered a mental health facility after the shootings.
He had also purchased smokeless powder and built pipe bombs with Farook, which the shooter left at the scene, investigators said.
Marquez claims that he stopped plotting with Farook in 2012 and kept his distance from the Pakistan national.
If convicted of all charges, he faces up to 50 years in federal prison.