(CBS) — Larry Nassar, the former USA Gymnastics doctor convicted of molesting young athletes, has likely been moved to another prison after he was assaulted behind bars. The Federal Bureau of Prisons website says Nassar is no longer at a federal penitentiary in Tucson, Arizona, where he was housed for the beginning of his 60-year prison sentence on child pornography charges. The disgraced ex-doctor is now being held at the Oklahoma Federal Transfer Center.

The Detroit News first reported details of Nassar’s transfer. It’s unclear when the transfer took place. Last month, Nassar’s attorneys said he was assaulted within hours of being placed in the general population at the Arizona prison. His counsel, however, did not specify the severity of the attack.

Ralph Miller, a retired Bureau of Prisons employee who specialized in sex offender cases, told Detroit News that the transfer likely followed the assault and an investigation showing that Nassar could not be safely housed at the facility. Miller said believes Nassar could be transferred to another high security prison in Florida or Indiana.

“This is a difficult case for the Bureau of Prisons in that Nassar’s case is highly publicized and he will be known to the inmate population no matter which facility is selected,” Miller told the publication. “Due to this, the Bureau of Prisons is likely to utilize all available high security facilities prior to reviewing him for placement in a medium with in excess of 30 years to still be served.”

Lawyers for Nassar unsuccessfully appealed his sentence and tried to get a new judge on the case. They accused Ingham County Circuit Judge Rosemarie Aquilina of using the nationally televised proceedings to “advance her own agenda” — advocating for policy initiatives and broader cultural change — and improperly agreeing to media interviews during the appeal period.

More than 300 women and girls have accused Nassar of sexually assaulting them, and many spoke out publicly during his sentencing and in interviews. Just last week, former Olympic gymnast Madison Kocian told “CBS This Morning” the athletes’ relationship with Nassar “was almost like a family member.” She described “a culture of fear, a culture of silence” at the team’s Karolyi Ranch training center, adding, “that’s what led him to be able to abuse us.”

Nassar treated campus athletes and many young gymnasts at his Michigan State office and worked for USA Gymnastics, which trains Olympians.