GRAND RAPIDS, Mich. – A Michigan sports doctor who admits he molested gymnasts and kept a staggering collection of child pornography was sentenced to 60 years in prison Thursday morning.

Larry Nassar was in federal court in Grand Rapids, Michigan, for his pornography sentence. He'll be punished in January in state court for sexual assault.

Nassar worked at Michigan State University and at USA Gymnastics, the Indianapolis-based group that trains Olympians.

Federal prosecutors were seeking the 60-year sentence.

Investigators found more than 37,000 images of child porn on Nassar's electronic devices. His lawyers say he "deeply regrets" his crimes.

Olympian McKayla Maroney calls Nassar a "monster" and is urging a judge to set the maximum sentence.

Nassar pleads guilty to child pornography charges

In July, Nassar pleaded guilty to the child pornography charges. The physician was arrested last year on the child pornography charges including receipt and attempted receipt of child pornography, possession of child pornography, and destruction and concealment of records and tangible objects.

Nassar agreed to plead guilty to all of those charges. As part of the plea agreement he was not prosecuted for sexual exploitation and attempted sexual exploitation of children, as well as interstate or international travel with intent and engaging in illicit sexual conduct. Those charges were related to an incident which is alleged to have occurred in Nassar's swimming pool with two children in the summer of 2015.

A court document alleged that on Sept. 18, 2004 and Dec. 1, 2004, Nassar received child pornography that was sent to him over the Internet. The document says that between Feb. 6, 2003 and Sept, 20, 2016, Nassar was in possession of computer disks and electronic files that had thousands of images of child pornography. Some of the images allegedly included a minor who was younger than 12 years old, officials said.

By pleading guilty, Nassar admitted he knowingly received child pornography, knew that the material was child pornography and that it had been shipped or transported in interstate or foreign commerce by any means, including a computer.