Three Americans repatriated to the United States from Congo were charged Wednesday by the U.S. Justice Department with staging an elaborate coup attempt aimed at overthrowing the African nation’s government.

A fourth man alleged by prosecutors to be a bomb-making expert was also charged for aiding the plot.

The complaint arises from the set of allegations that resulted in three of the defendants being detained in Congo and receiving death sentences that were later commuted to punishments of life imprisonment.

In the culmination of a long-running FBI investigation, the Justice Department accused the men of providing training, weapons, equipment and other support to a rebel army that was formed to try to overthrow the government last year.

Among the three Americans was 22-year-old Marcel Malanga, son of opposition figure Christian Malanga, who led the foiled coup attempt that targeted the presidential palace in Kinshasa. The elder Malanga, who livestreamed from the palace during the attempt, was later killed while resisting arrest, Congolese authorities said.

Prosecutors say the goal of the plot was to establish a new government known as the New Zaire and install Christian Malanga as its president. The younger Malanga identified himself as the “Chief of Staff of the Zaire army” and acted as a leader of the rebel forces, court documents say.

Defendants Marcel Malanga, Tyler Thompson, 22, and Benjamin Zalman-Polun, 37, were initially sentenced to death, but that was commuted to life sentences prior to their return to the U.S. They were expected to make their first court appearance in Brooklyn. Joseph Peter Moesser, 67, was due to appear in Salt Lake City Thursday.