A federal inmate was charged on Friday with attempted murder and other offenses for allegedly stabbing Derek Chauvin, the former Minneapolis police officer convicted in the death of George Floyd, the U.S. Justice Department said in a statement.

The complaint alleges that while incarcerated at Federal Correctional Institution Tucson, John Turscak, 52, stabbed Chauvin about 22 times “with an improvised knife,” prosecutors said.

Turscak was charged with attempted murder, assault with intent to commit murder, assault with a dangerous weapon, and assault resulting in serious bodily injury, according to prosecutors.

The investigation in the case was conducted by the FBI.

Attempted murder and assault with intent to commit murder violations each carry maximum penalties of 20 years incarceration, while assault with a dangerous weapon and assault resulting in serious bodily injury each carry maximum penalties of 10 years.

Chauvin was expected to survive following the attack last week in a prison in Arizona, the Minnesota Attorney General’s office said earlier.