Detectives investigating alleged sexual assaults by former University of Southern California campus gynecologist George Tyndall have now presented 53 cases to prosecutors, but so far, no criminal charges have been filed.
The Los Angeles County District Attorney's Office told NBC4 Friday the cases are under review.
Tyndall and USC have been sued by hundreds of former patients who allege they were touched inappropriately during exams at the Engemann Student Health Center between 1998 and 2016.
Last week Tyndall agreed to temporarily surrender his medical license while the Medical Board of California reviews the allegations.
Tyndall has denied wrongdoing. His attorney, Leonard Levine, has said Tyndall's actions during the exams were consistent with, 'the standard of care.'
The pace of the criminal investigation has frustrated some of the victims, who said they were interviewed both by LAPD detectives and prosecutors.
"This may be the most exhaustive and largest individual investigation of an alleged predator that the LAPD has ever done," explained plaintiff's attorney John Manly, whose firm in Irvine represents well over 100 women.
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"While our clients are perplexed as to why no charges have been filed, we continue to believe the DA's office is going to do the right thing."
In June LAPD detectives assigned to the Robbery-Homicide Division served a search warrant at Tyndall's condo on Wilshire Boulevard in the Westlake District near downtown.
Tyndall was not arrested.
He resigned from USC following an internal investigation of complaints. USC officials have denied there was a cover up.
In an open letter to faculty and staff in May, USC Provost Michael Quick said top administrators did not know about the complaints until 2016.
"It is true that our system failed, but it is important that you know that this claim of a cover-up is patently false," Quick wrote. "We would never knowingly put students in harm's way."
USC established a hotline for complaints about Tyndall and has offered free counseling to his former patients.