WASHINGTON, Jan. 24 (Xinhua) -- After a week-long hearing that featured statements from 156 of his accusers, former US Olympic gymnastics doctor Larry Nassar, was sentenced on Wednesday to 40 to 175 years in prison for molesting young girls under the guise of treatment.

"I just signed your death warrant," Judge Rosemarie Aquilina said in the Ingham County, Michigan courtroom: "You do not deserve to walk outside a prison ever again. You have done nothing to control those urges and anywhere you walk, destruction will occur to those most vulnerable."

Although Nassar only admitted to seven instances of abuse in the case, Aquilina allowed other victims to speak at his sentencing. A total of 156 victims have appeared in court in Lansing, Michigan, or had their statements read by others since last week, including Olympic gold medalists such as Aly Raisman and McKayla Maroney.

The last witness to speak at Nassar's sentencing hearing was Rachael Denhollander, one of the first women to publicly identify herself as one of Nassar's young victims. She said she was sexually abused by the doctor when she was a 15-year-old gymnast in Michigan.

"Larry, I can call what you did evil and wicked because it was," Denhollander said on Wednesday. "You have become a man ruled by selfish and perverted desires."

Prosecutor Angela Povilaitis called Nassar "possibly the most prolific serial child sex abuser in history". She said the "breadth and ripple" of Nassar's sexual abuse is "nearly infinite".

Nassar also offered a short statement before the sentencing in court, apologizing and saying that hearing seven days of victim impact statements had shaken him to his core.

"There are no words that can describe the depth and breadth of how sorry I am for what has occurred," Nassar said. "An apology to all of you is impossible to write and convey. I will carry your words with me for the rest of my days."

Besides the seven counts of first-degree sexual assault to which Nassar pleaded guilty to last November in Ingham County, he also faces another three additional charges in Eaton County, where he will be sentenced next week. Nassar has already been sentenced to 60 years in prison for child pornography crimes last year.

The case also set off investigations into protection for athletes at USA Gymnastics and at Michigan State University in Lansing, which also employed Nassar.

USA Gymnastics Board of Directors executive leadership -- Chairman Paul Parilla, Vice Chairman Jay Binder and Treasurer Bitsy Kelley -- announced their resignations on Monday. Steve Penny also resigned as USA Gymnastics President last year. There are also calls that Lou Anna Simon, President of Michigan State University, should resign or be fired by the school's governing board.

The US Olympic Committee Wednesday announced an independent investigation intended to determine how the sexual abuse from Nassar could have gone for as long as it did.