The U.S. government's key witness in a case alleging a Turkish scheme to do business with Iran despite sanctions may be put in the witness protection program because the people he exposes “might use violence” against him, according to a plea agreement reviewed by The Daily Beast.

Reza Zarrab is a Turkish businessman who was set to go on trial in a Manhattan federal court for using the U.S. financial system to help Turkey buy oil from Iran, against U.S. law prohibiting business with Tehran. Instead, Zarrab pleaded guilty to charges of bank fraud, money launder, bribery, and sanctions violations in exchange for leniency from prosecutors with whom he is cooperating.

It's not without a potentially serious price though.

“Should the defendant's cooperation present a significanct risk of physical harm, this Office...will take steps that it determines to be reasonable and necessary to attempt to ensure his safety and that of his family and loved ones,” the U.S. Attorney's Office for the Southern District of New York wrote in Zarrab’s plea agreement.

“These steps may include application to the Witness Security Program of the United States Marshals Service” whereby Zarrab and his family could be “relocated under a new identitiy,” the U.S. Attorney's Office said, adding it's ultimately up to the Justice Department.

Zarrab, a Turkish citizen arrested in Miami last year during a trip to Disney World with his family, would first have to convincce the U.S. not to deport him following his testimony in the trial of co-defendant Mehmet Hakan Atilla.

After Zarrab started testifying last week, Turkey seized his properties as punishment. On the stand, Zarrab implicated high-ranking Turkish officials, including President Erdogan, in the sanctions-violations scheme.