The man who bought the rifles used in the San Bernardino terrorist attack last month pleaded not guilty to federal charges accusing him of conspiring with one of the shooters and providing material to support terrorists.

Enrique Marquez Jr., 24, appeared in federal court in Riverside, California, on Wednesday, where he pled "not guilty" to the five-count indictment, reports CBS News. His charges include allegedly buying rifles used in the attack and conspiring to support terrorism.

Marquez was arrested about two weeks after his longtime friend and neighbor, Syed Rizwan Farook, and his wife opened fire at the Inland Regional Center during a Christmas party on Dec. 2. The married couple killed 14 people and wounded 21 others before they were killed by police. It was later discovered that the suspects were individually self-radicalized long before they got married and moved to California.

After 10 days of questioning by investigators, FBI officials said Marquez and Farook became friends over a decade ago and that that Farook converted him to Islam when they were teenagers. The shooter also indoctrinated Marquez with violent Islamic extremism.

According to federal authorities, Marquez admitted that he and Farook once plotted a terror attack on a community college and a highway in Southern California during rush hour. As a result, he has been charged with conspiring to carry out other terrorist attacks in 2012, reports The Washington Post. He is also facing charges for making false statements while purchasing the assault rifles used in the attack and lying on immigration forms about marrying a Russian woman whose sister is married to Farook's brother.

Although Marquez was not involved in the killings, authorities argue that his failure to warn authorities about Farook and his purchase of two rifles for him in 2011 and 2012 ultimately led to deadly consequences.

His trial is set to begin Feb. 23. If convicted, he could face up to 50 years behind bars.