A sports doctor who worked for USA gymnastics and Michigan State University has been sentenced to 60 years in jail after he was found to have knowingly amassed 37,000 images of child pornography.

The child porn was found on 54-year-old Larry Nassar's electronic devices in 2016 while he was being investigated over sexual assault. Nassar has admitted to molesting girls in his care when they sought treatment with him.

Olympic level gymnasts had accused Nassar of molesting them when they were children. Gold medal winning gymnast McKayla Maroney said in a statement in October that Nassar had molested her from the time she was 13.

In a letter to District Judge Janet Neff, Maroney said that Nassar was a "monster" and said he had "left scars on my psyche that may never go away". Neff said that Nassar "should never again have access to children."

The sentencing on Thursday 7 December was only the first of three criminal cases Nassar is facing. He is also being sued by over 100 women.

Nassar pleaded guilty on November 29 to charges of molesting teen and pre-teen gymnasts who sought help for back and hip injuries. "I'm so horribly sorry that this was like a match that turned into a forest fire out of control," said a judge in a third case in Ingham County.

The former elite sports doctor will be sentenced for the other two cases in January, he's unlikely to ever see outside a prison again.

USA Gymnastics, which oversees and trains the national team, is also a defendant in several of the lawsuits women have brought against Nassar.

In August, leading gymnast Aly Raisman accused the body of neglecting its duties and a wide-ranging report by the Indianapolis Star said the organisation routinely turned a blind eye to allegations of abuse and relied "on a policy that enabled predators to abuse gymnasts".