Al Goldis/Associated Press

Michigan State athletic director Mark Hollis stepped down Friday in apparent response to sexual assault scandals related to Larry Nassar and the football and basketball programs, according to Chris Solari of the Detroit Free Press.

Lou Ann Simon also resigned as MSU president Wednesday, per ESPN.com.

Nassar, who served as a physician at Michigan State as well as for USA Gymnastics, was sentenced to 45 to 175 years in prison Wednesday after pleading guilty to seven counts of first-degree criminal sexual conduct. He is also awaiting sentencing on a further three counts.

"I know this is the right time," Hollis said. He added that he planned to retire in the near future regardless of the Nassar situation, according to Solari.

He also said he was not pressured to act and that "many people" told him not to step away.

When asked about Nassar, Solari said he doesn't believe he ever met him during his time as AD, per Solari.

Although Hollis showed remorse for Nassar's victims, he wasn't regretful about how he handled any situation as athletic director, saying, "Every decision I made was a good one at the time I made it."

In addition to the Nassar situation, Paula Lavigne and Nicole Noren of ESPN's Outside the Lines published a report Friday detailing efforts made by Michigan State to withhold information regarding cases involving sexual assault and violence against women.

The report said that MSU went to great lengths to hide the identity of athletes who were accused of crimes. The investigation also found that at least 16 Michigan State football players faced allegations of sexual assault or violence against women during head coach Mark Dantonio's tenure.

With regard to head coach Tom Izzo's basketball program, former undergraduate assistant Travis Walton was alleged to have punched one woman and sexually assaulted another. Former MSU basketball players Adreian Payne and Keith Appling were also alleged to have raped a former MSU student in 2010, but charges were not filed and neither player was disciplined.

The Athletic's The All-American tweeted Hollis' full statement regarding his retirement:

According to ESPN.com's Dan Murphy, Nassar was allowed to continue seeing patients at Michigan State for 19 months in 2014 and 2015 despite being under investigation for sexual abuse.

Murphy also reported that Michigan State osteopathic school dean Dr. William Strampel implemented guidelines for Nassar in the wake of the initial investigation, but they were poorly applied. The physician was told he needed a chaperone in the room during his examinations and to avoid skin-to-skin contact with patients, but Nassar's direct superior was not informed of these directives, and they were not consistently enforced.

Nassar graduated from Michigan State in 1993 and eventually began serving as an assistant professor and physician at the school. He was also the national medical coordinator for USA Gymnastics.

Over 150 women and girls said Nassar sexually abused them, including Olympic gold medal-winning gymnasts Aly Raisman, McKayla Maroney, Gabby Douglas, Simone Biles and Jordyn Wieber.

In addition to his most recent sentence, Nassar is serving 60 years in prison on child pornography charges.

Hollis had served as Michigan State's athletic director since 2008. He had been part of the MSU athletic department since 1995 and graduated from the school in 1985.