Larry Nassar faces 22 new sexual assault charges. More than half directly relate to his work as a doctor at Michigan State University's Sports Medicine practice and the rest are tied to his work with a gymnastics club.

Police secured warrants today in 55th District Court in Mason and 56A District Court in Charlotte for the charges, which come more than five months after the large-scale sexual assault investigation into the fired university doctor began. He is expected to be arraigned on Thursday.

Previous criminal charges in Ingham County and in federal court did not relate to his role as a doctor.

The Ingham County charges relate to medical appointments at Michigan State University's Sports medicine clinic offices or after-hours at Nassar's home in Holt, according to court documents. The Eaton County charges relate to Nassar's work at Geddert’s Twistars Gymnastics Club in Dimondale.

The accusations involve procedures that included digital vaginal and anal penetration, according to testimony.

Nassar faces five counts of first-degree criminal sexual conduct involving a sexual penetration of a victim under age 13, which carry a 25-year mandatory minimum and up to life in prison.

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

He also faces 17 counts of first-degree criminal sexual conduct involving penetration of a victim between ages 13 and 16, which carry a life senence. In a press release Attorney General Bill Schuette's office said charges apply "when the alleged assailant is in a position of authority over the victim and used the authority to coerce the victim to submit or when the actor causes personal injury to the victim and engaged in the medical treatment or examination of the victim in a manner or for purposes that are medically recognized as unethical or unacceptable."

"Dr. Nassar preyed on these young girls, he used his status and authority to engage in horrid sexual assaults under the guise of medical procedures. He violated the oath that every doctor takes to do no harm,” said Schuette in a statement released as a news conference began this afternoon.

An additional 14 counts also were authorized as potential alternate charges for some of the 22 total charges.

Many of the women connected to the Ingham County charges were minors at the time of the incidents, and Michigan State University police Det. Sgt. Andrea Munford testified that Nassar did not obtain consent from the patients or their parents and did not wear gloves.

Some of the women told police Nassar was sexually aroused during the procedures and that at times the penetration lasted up to 30 minutes. Some of the women also told police Nassar digitally penetrated them in the presence of their parents, who were blocked from full view of the doctor's actions.

Ingham County Magistrate Mark Blumer signed warrants this morning at the end of a 20-minute hearing.

"I further find that there is no reasonable reason to believe that the processes followed by the defendant were legitimate medical practices," he said. "And because of that I find him to be an immediate danger to the public and I am denying bond pending arraignment on these charges."

Nassar is in federal custody and is being held without bail on other charges.

Matt Newburg, one of Nassar's attorneys, declined to comment. Nassar has previously denied any wrongdoing and said he performed legitimate medical procedures.

Schuette, whose office is prosecuting Nassar, and Michigan State University Police Chief Jim Dunlap, whose department is leading the investigation, appeared together at today's news conference.

“The allegations of sexual assault against Dr. Nassar continue to increase nearly every day, and we remain constantly in contact with the victims as we move forward,” Dunlap said in a statement. “Our priority is getting justice for the survivors and we are determined to make certain that occurs. I encourage anyone who may have been a victim of Larry Nassar to come forward by contacting the MSU Police Department.”

Many of the accusers told police they began seeing Nassar for pain in their hips, backs, hamstrings, or for other issues. They were identified in affidavits filed with the courts by letters of the alphabet.

Victim F saw Nassar more than 30 times over several years, Munford testified in Ingham County. During the first appointment, Victim F told police that Nassar explained to her and her mother that he knew of an Australian technique, which he didn’t explain, Munford testified.

"Victim F stated that when her mother was in the room Nassar covered her with a sheet," Munford testified. "When her mother stood up to see what was happening, Nassar stopped penetrating her."

The woman told police that Nassar’s penetration became more "aggressive and invasive" over time and she would often grit her teeth to prevent "yelping in pain," Munford said.

The penetration often lasted 45 minutes, Munford added, and there were times during the penetration that Nassar had a hand on the woman’s breasts.

"Victim F also saw Nassar with a noticeable erection," the detective testified. "During one appointment he told her to shave her pubic hair. On another occasion, while penetrating her, he talked about fingering his ex-girlfriend in the same way."

Munford testified that Nassar made several other inappropriate comments.

Since September, when the Indianapolis Star detailed sexual assault allegations against Nassar from two women, more than 60 women or girls have reported to law enforcement that Nassar sexually abused them, officials have said.

Nassar worked for decades with Michigan State University and with USA Gymnastics. The university fired him in September. He left USA Gymastics in fall 2015 with little notice.

More than 40 women or girls have filed lawsuits against MSU, Nassar, USA Gymnastics or Dimondale-based Twistars gymnastics club and say they were sexually assaulted during medical appointments. The procedures in question, according to court documents, included digital vaginal and anal penetration.

The criminal investigation of Nassar that started in September isn't the first the doctor has faced.

Meridian Township police investigated him in 2004, but a request for charges was never sent to prosecutors. Police have declined to release records in that investigation, saying it was reopened last year.

University police investigated Nassar in 2014 after a then recent graduate said he sexually assaulted her during an appointment at his campus office for hip pain treatment. The Ingham County Prosecuting Attorney's Office, then led by Stuart Dunnings III, declined to issue charges. Prosecutors and police have declined to release records because that case also has been reopened.

That 2014 complaint also prompted MSU to open an internal Title IX investigation, and MSU ultimately cleared Nassar, in part, based on the opinions of four medical experts with close ties to Nassar and the university.

Nassar, 53, of Holt, was charged in November with three counts of first-degree criminal sexual conduct. The charges relate to instances in his home between 1998 to 2005 with a child who is now a woman in her 20s. She has testified that Nassar sexually assaulted her, including instances when he penetrated her vagina with his fingers when her family visited his.

Those charges carry maximum sentences of life in prison.

Nassar also faces three federal charges for obtaining, possessing or destroying child pornography images or video. An FBI agent testified in December that computers and hard drives found on Nassar's property in Holt contained at least 37,000 images or videos of child pornography, as well as videos that showed Nassar sexually assaulting young girls in a swimming pool.

Contact Matt Mencarini at (517) 267-1347 or Follow him on Twitter @MattMencarini. Contact him on Signal, a messaging app with end-to-end encryption, at 517-281-1939.