Former Michigan State University doctor Larry Nassar agreed to plead guilty to federal child pornography charges.

Nassar, 53, of Holt, was indicted in December on charges of obtaining and possessing child pornography. Months later, the U.S. Attorney's Office added a third charge that alleged Nassar had images or files destroyed.

He signed an agreement to plead guilty to all three charges, according a copy of the agreement obtained by the Lansing State Journal. The plea deal does not include a sentence agreement.

Each charge carries a sentence of five to 20 years in prison.

The formal plea agreement has not been filed in federal court, and no plea hearing has been scheduled. His next scheduled appearance is for August.

Matt Newburg, one of Nassar's attorneys, declined to comment.

In December, days after Nassar was arrested, an FBI agent testified at a detention hearing that, during a search of Nassar's Holt property, law enforcement found hard drives, some of which were in a trash can outside the home, that contained at least 37,000 images and videos of child pornography.

The agent also testified that videos were found that appeared to show Nassar sexually assaulting young girls in a pool.

Nassar worked at MSU for nearly 20 years. The university fired him on Sept. 20 but on Sept. 16 sent him a letter stating that, based on new sexual assault allegations and his withholding of information about a 2004 police investigation, the university was considering firing him.

On Sept. 19, according to the plea agreement, Nassar took his work laptop to a computer service store and paid $49 to have all the data, including the operating system, permanently deleted.

The plea agreement states that Nassar had the laptop erased and put the hard drives in a trash can "to impede and obstruct" the investigation.

The plea deal includes an agreement that Nassar will register as a sex offender and an agreement that the U.S. Attorney's Office for the Western District of Michigan will not prosecute him for alleged sexual exploitation or attempted sexual exploitation of children, including an incident in 2015 in his swimming pool.

Related:Larry Nassar and a career filled with ‘silenced’ voices

Related:At MSU: Assault, harassment and secrecy

Related:For Nassar accusers, testifying 'takes a lot of courage'

Nassar also worked with USA Gymnastics. He left the organization in fall 2015 with little notice.

The plea agreement will resolve one of four criminal cases against Nassar, leaving three state sexual assault cases that are being prosecuted by the Michigan Attorney General's Office.

Those three cases include 22 first-degree criminal sexual conduct charges, with all but three relating to his former role as a doctor. Nassar faces up to life in prison if convicted on the state charges.

He's also being sued by more than 115 women and girls, all but one of whom say in court records that he sexually assaulted them during medical appointments. Many have said the abuse happened at MSU, at USA Gymnastics events or at Twistars gymnastics club in Dimondale.

MSU, USA Gymnastics and Twistars have all been named as co-defendants in some of the lawsuits.

Here’s a timeline of Nassar’s decades-long career and the allegations against him. This will continue to be updated.

Here's a map of key people and connections in the Nassar cases. This will continue to be updated.

Contact Matt Mencarini at (517) 267-1347 or mmencarini@lsj.com. Follow him on Twitter @MattMencarini.