EAST LANSING, Mich. -- Michigan Attorney General Bill Schuette vowed a thorough investigation Saturday into Michigan State University in the wake of the Larry Nassar sex abuse scandal. Schuette, who is running for governor, said "it is abundantly clear that a full and complete investigation of what happened at Michigan State from the president's office down is required."

"Let's be very clear: no individual in no department at Michigan State University is off limits," Schuette said. "I've often said that there is one system of justice ... I've instructed my department this is priority one -- this investigation."

"We will put a bright light at every corner of the university," he said.

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Independent special prosecutor and retired Kent County Prosecutor William Forsyth is leading the probe. Michigan State Police are assisting, and Assistant Attorney General Christina Grossi was named project manager.

"How was he allowed to engage in this behavior for almost 20 years?" Forsyth asked Saturday, referring to Nassar. "How could he victimize so many innocent young girls and young women for that long a period of time and no one caught him and stopped him?"

Forsyth said the investigation intends to answers those and other questions.

Schuette and Forsyth spoke at a press conference a day after MSU's athletic director retired Friday following the university president's resignation over the school's handling of sexual abuse allegations against Nassar, a former Michigan State employee and gymnastics doctor for the U.S. Olympic team.

Mark Hollis, who had been in the job for 10 years, disclosed the move Friday during a meeting with a small group of reporters on campus. He was asked why he would not stay on.

"Because I care," Hollis said, holding back tears. "When you look at the scope of everything, that's the reason I made a choice to retire now. And I hope that has a little bit, a little bit, of helping that healing process."

Hours later, the university named its vice president to serve as acting president after the departure of President Lou Anna Simon, who submitted her resignation Wednesday. Bill Beekman is expected to serve briefly in the role until the board of trustees can hire an interim president and then a permanent leader.

Also Friday, USA Gymnastics confirmed Friday that its entire board of directors would resign as requested by the U.S. Olympic Committee. The USOC had threatened to decertify the organization, which besides picking U.S. national teams is the umbrella organization for hundreds of clubs across the country.

Some of the nation's top gymnasts, including Olympians Aly Raisman, McKayla Maroney, Simone Biles and Jordyn Wieber, said they were among Nassar's victims.

At the university board's meeting, Chairman Brian Breslin said it was "clear that MSU has not been focused enough on the victims." The trustees, he said, want to resume discussions with those who have sued the school to "reach a fair and just conclusion." Talks broke down last year.

Trustee Brian Mosallam addressed his remarks toward the victims: "I am so truly sorry. We failed you."

Nassar was sentenced this week to 40 to 175 years in prison for molesting young girls and women under the guise of medical treatment. Several of the 150-plus victims who spoke at his sentencing hearing were former athletes at MSU, and many victims accused the university of mishandling past complaints about Nassar.

Gov. Rick Snyder said Friday he was mulling an inquiry into the university, depending on whether it would interfere with other investigations such as the attorney general's. Under the state constitution, the governor can remove or suspend public officers for "gross neglect of duty," corruption or "other misfeasance or malfeasance."

"The governor hasn't seen enough done for the survivors after everything they've gone through," spokeswoman Anna Heaton said. "He wants to make sure that something is being done."

U.S. Education Secretary Betsy DeVos confirmed Friday that her agency is also investigating the Nassar scandal. She said in a statement that what happened at the school is "abhorrent" and "cannot happen ever again - there or anywhere."

The Education Department was already reviewing separate complaints about the school's compliance with Title IX, the law that requires public schools to offer equal opportunities to both genders, and compliance with requirements about providing campus crime and security information.

The board expressed support for Simon before her resignation, but she faced pressure from many students, faculty and legislators. While there has been no evidence that Simon or Hollis knew of Nassar's sexual abuse, some of the women and girls who accused him said they complained to university employees as far back as the late 1990s.

Board members, who are elected in statewide votes, have also come under intense scrutiny. Two announced they will not seek re-election. Another, Joel Ferguson, apologized at the meeting for conducting an interview in which he said there was more going on at Michigan State than "this Nassar thing."

The university faces lawsuits from more than 130 victims. Ferguson previously had said victims were ambulance chasers seeking a payday. The school resisted calls for an independent investigation before asking Schuette for a review a week ago.

Dozens of Michigan State students gathered Friday evening on campus to protest the school's handling of the Nassar allegations. Some were expected to march to the Breslin Center where the men's basketball team was hosting Wisconsin Friday night. Organizers called for students attending the game to wear teal-colored T-shirts in the "Izzone," a vocal student cheering section named after head basketball coach Tom Izzo.

In a recent filing, Michigan State asked a judge to dismiss the lawsuits on technical grounds. The school says it has immunity under state law and that the majority of victims were not MSU students at the time of the alleged assaults.

"These arguments can seem disrespectful" to victims, but a defense is required by Michigan State's insurers, Simon wrote last week in a campus-wide email. She added, "We have the utmost respect and sympathy" for victims.

The board last month authorized the creation of a $10 million fund to offer victims counseling and mental health services.

A Title IX probe conducted by the university cleared Nassar of sexual assault allegations in 2014. He was advised by the school to avoid being alone with patients while treating their "sensitive areas," but the school did not follow up on and enforce its request.

At least 12 reported assaults occurred after the investigation ended, according to a university police report that was provided to the FBI for review by the U.S. attorney.

Hollis said he did not know about the 2014 investigation and has told as much to the FBI and campus police.