Nassar, 54, received a 60-year federal prison sentence in December for child pornography charges.

Judge Rosemarie Aquilina said Nassar's "decision to assault was precise, calculated, manipulative, devious, despicable."

"It is my honor and privilege to sentence you. You do not deserve to walk outside a prison ever again," she said. "You have done nothing to control those urges and anywhere you walk, destruction will occur to those most vulnerable."

Aquilina added: "I just signed your death warrant."

Nassar gave a statement before his sentencing on Wednesday, turning at times to address the courtroom gallery.

"Your words these past several days have had a significant emotional effect on myself," he said. "I will carry your words with me for the rest of my days."

Prosecutor Angela Povilaitis had asked Aquilina to sentence Nassar to up to 125 years -- one year for every person who had submitted a police report at the time of his guilty plea. A plea deal set sentencing guidelines at 25-40 years.