Derek Chauvin was stabbed in prison 22 times by a former gang leader and one-time FBI informant who told investigators he targeted the ex-Minneapolis police officer because of his notoriety for killing George Floyd, federal prosecutors said Friday.

John Turscak was charged with attempted murder a week after the Nov. 24 attack at the Federal Correctional Institution in Tucson, Arizona. He told correctional officers he would have killed Chauvin had they not responded so quickly, prosecutors said.

Turscak, who is serving a 30-year sentence for crimes committed while a member of the Mexican Mafia prison gang, told investigators he thought about attacking Chauvin for a month because he is a high-profile inmate but denied wanting to kill him, prosecutors said.