When members of the Gambino crime family correctly suspected in the late 1990s that a nephew of one of their most powerful captains was cooperating with the government, they plotted to kill him, the authorities say.

But before carrying out the plot, they sought permission from the captain, who was in prison at the time.

The captain, Daniel Marino, authorized the killing, federal prosecutors in Manhattan said Tuesday.

The nephew, who was 31, was lured to a strip club on Staten Island, and was shot and killed, the prosecutors said.

The killing was just one of a series of crimes included in an indictment unsealed on Tuesday against 14 members and associates of the Gambino family. The cases represent “literally decades of criminality,” as Preet Bharara, the United States attorney for the Southern District of New York, put it at a news conference.