Washington

Washington (CNN) -- A 29-year-old man from Morocco was arrested Friday and charged with attempting to bomb the U.S. Capitol building in a suicide attack, authorities said.

Suspect Amine El Khalifi made an initial appearance in court and, if convicted, faces a maximum penalty of life in prison, according to the Justice Department.

He allegedly went to a parking garage near the Capitol on Friday and received what he thought was a vest with explosives and a firearm, both of which had been rendered inoperable by law enforcement. He was arrested before leaving the garage.

"Today's case underscores the continuing threat we face from homegrown violent extremists," said Assistant Attorney General for National Security Lisa Monaco. "Thanks to a coordinated law enforcement effort, El Khalifi's alleged plot was thwarted before anyone was harmed."

The suspect was charged with attempting to use a weapon of mass destruction against government property. Authorities say the public was never in any danger.

During his initial court appearance, he wore blue pants and a green T-shirt with the words "Ready in Season" on the back. El Khalifi had short black hair, a trimmed, thin beard and tattoos on his inner arm. He stood straight, showed no emotion and did not speak.

The suspect, an immigrant from Morocco, is in the United States illegally, according to the Justice Department.

He had been closely monitored as part of a lengthy and extensive undercover operation, police said, adding that U.S. Capitol Police had been "intimately" involved in the investigation.

One law enforcement official, who spoke on the condition of anonymity, said the suspect entered the United States legally in June 1999 under a B2 visa. The visa expired later that same year and he has been in the United States illegally ever since, the official said.

That same official told CNN that law enforcement is searching two locations in Virginia in connection to the investigation -- one in Arlington, the other in Alexandria.

A second law enforcement official said El Khalifi is not connected to a terrorist organization and was acting alone.

El Khalifi thought he had met al Qaeda members who would assist him, but in fact he was dealing with undercover FBI agents, said the second source, who declined to say whether the FBI has audio or video recordings of the suspect talking to undercover agents about his plans.

A third source briefed on the matter said the suspect was identified through an existing criminal, not terrorism investigation. When asked about possible entrapment, the U.S. government source said the suspect went out on his own to buy component pieces for an improvised explosive device.

After news of the arrest broke, House Majority Leader Eric Cantor hailed the work of the FBI and the U.S. Capitol Police in thwarting the alleged attack.

"These brave members of our law enforcement community make daily sacrifices in their work to keep us safe and deserve tremendous credit for their efforts leading up to today's successful sting," he said.

In September last year, a federal grand jury indicted a man for allegedly plotting to use large remote-controlled model airplanes filled with explosives to attack the Capitol and the Pentagon.

A man was arrested in September 2008 two blocks from the Capitol after an officer spotted a rifle in his car.

And in July 1998, a gunman fired shots in the Capitol building, killing two U.S. Capitol Police officers.