A Washington, D.C., Metro Transit police officer who was a convert to Islam and once dressed up as Jihadi John for Halloween was charged on Wednesday with attempting to provide material support to ISIS -- the first time a law enforcement officer has been charged with an ISIS-related crime.

Virginia resident Nicholas Young, 36, who had served with the department since 2003, was arrested Wednesday morning by FBI agents at Metro Transit Police headquarters in Washington, DC.

The lanky, slim-built 36 year old was dressed in a prison issue white t-shirt and dark pants and sported long hair as he made his initial appearance in court Wednesday afternoon. No attorney was present.

Young spoke only to request a public defender be appointed to represent him.

He will be held in Alexandria until his detention hearing, which is set for Friday at 2 p.m. If convicted, he faces up to 20 years in prison, a $250,000 fine and a lifetime of supervised release.

Authorities allege in a criminal complaint unsealed Wednesday that Young attempted to send money to ISIS through mobile-based gift cards using an unnamed messaging service the terror group utilizes for recruiting purposes. 

The $245 digital transaction, which was actually sent to an undercover FBI agent in July, was redeemed by the agency.

Despite Wednesday’s arrest, the U.S. Attorney’s Office said there was never any threat to the public or a plot by Young to target the public transit system he was hired to protect.

Young had been under FBI investigation since 2010, when the Metro Transit Police Department alerted the feds to suspicions over the former police officer. During the investigation, the FBI kept extremely close tabs on Young through the use of undercover agents and confidential informants, a source told Fox News.

Investigators also interviewed Young several times during the course of the investigation.

Court documents paint the story of an individual with ties to suspicious individuals and with terrorist aspirations abroad.

The criminal complaint connects Young to two convicted Washington, DC-area terrorists, Zachary Chesser and Amine El Khalifi.

Chesser was sentenced in federal court in 2011 to 25 years in prison for aiding Al Qaeda affiliate Al Shabaab. He is also known for threatening the creators of South Park for the show's depiction of the prophet Mohamed. Khalifi was arrested in 2012 for attempting to detonate an explosive vest in the U.S. Capitol Building and was eventually sentenced to 30 years in prison for his crimes.

Court documents show federal investigators also questioned Young about trips he had taken to Libya in 2011. Young told FBI agents he traveled twice to the North African nation to assist rebels attempting to overthrow the regime of then-dictator Muammar Qaddafi.

A baggage search by Customs and Border Protection on one of Young’s outbound trips revealed he had traveled with body armor, a Kevlar helmet, and “several other military-style items,” according to the criminal complaint.

Young is also alleged to have maintained a large cache of firearms, including numerous rifles and handguns at his home.

His alleged terrorist leanings were thrown further into the spotlight in 2015 when he admitted to interviewers at the Metro Transit Police Department that he dressed up as Jihadi John for Halloween in 2014. According to the criminal complaint, as part of his costume “Young stuffed an orange jumpsuit with paper to portray a headless hostage, and he carried that around with him throughout the party.”

During that same interview, Young admitted to having previously dressed up as a Nazi and to collecting Nazi memorabilia as well as possessing a tattoo of a German eagle on his neck.

"Since I received my first briefing on this matter, [Metro Transit Police] Chief [Ronald] Pavlik and I have worked hand-in-glove with the FBI in the interest of public safety and to ensure that this individual would be brought to justice," Metro General Manager/CEO Paul Wiedefeld said in a statement.

Young's employment with the metro police was "terminated" Wednesday, according to a memo sent to metro staffers.

Matthew Dean is Fox News Channel's Department of Justice & Federal Law Enforcement producer. Follow him on Twitter @MattFirewall.