PHILADELPHIA — A Liberian accused of war crimes during the country’s first civil war falsely told an immigration official he was being persecuted in his homeland so he could enter the U.S., a federal prosecutor said Tuesday at the start of his fraud trial.

Mohammed Jabbateh, 51, is charged with immigration fraud and perjury over accusations that he lied about his history as a high-ranking member of Liberian rebel groups when he was seeking asylum and residency in the U.S. nearly two decades ago.

“You can’t commit heinous war crimes in your home country, then come to this country and try and stay here and lie about those crimes,” said Assistant U.S. Attorney Nelson Thayer Jr., who rifled off snippets of stories from witnesses who claim to have seen Jabbateh commit or order his fighters to kill civilians and conscript child soldiers and sex slaves.

Jabbateh, known as “Jungle Jabbah,” had been living outside Philadelphia and was arrested last year. He stared blankly at the jury with a clenched fist over his mouth as Thayer relayed a witness’ story about how he ordered his soldiers to strip a man naked and leave him tied up on the street for complaining that his rebels stole rice from his son.

Jabbateh’s attorney, Gregory Pagano, maintained that his client never lied to immigration officials, saying that he came to the U.S. because he was jailed without food for weeks.

“This man has the scars to prove what happened to him over there,” Pagano said. He also questioned the legitimacy of the government’s witnesses, claiming they have tribal and ethnic alliances that put them at odds with Jabbateh and the groups he’s accused of leading.

Jabbateh hasn’t denied being known as “Jungle Jabbah” and previously told an immigration official he was assigned as a security guard to a rebel leader. His lawyer said the nickname was a childhood moniker.

Near the end of the hearing at U.S. District Court in Philadelphia, prosecutors called their second witness, a Liberian woman who said she was forced into a sexual relationship with Jabbateh. The defendant looked down and fiddled with a stack of papers on the desk in front of him as she answered questions through an interpreter.

The trial of Jabbateh is one of a handful of legal efforts to hold people accountable for atrocities carried out during the civil wars that began in 1989 and devastated the west African country for much of the 1990s and early 2000s.