When Baton Rouge Police Department (BRPD) leadership found out about the allegations of the "brave cave,Grant Preston" the police chief immediately went to the FBI in August, according to a source familiar with the investigation.

The police department faces several lawsuits over the treatment of detainees, including at a now-shuttered police warehouse that officers allegedly called the "brave cave," according to the complaints.

It is exceedingly rare for a police chief to go to the FBI and ask for an investigation into their own department.

The FBI announced over the weekend, they are investigating the Baton Rouge Police Department following allegations that some officers "abused their authority."

The New Orleans FBI Field Office, the Civil Rights Division and the U.S. Attorney's Office for the Middle District of Louisiana have opened the probe, with investigators "reviewing the matter for potential federal violations," FBI New Orleans said in a statement on Friday, while urging anyone with information on the case to contact them.

Additionally, according to the source, the Baton Rouge Police Department has both an administrative and criminal investigation into the allegations ongoing.

In a statement to ABC News, the Baton Rouge Police Department said they are "committed to addressing these troubling accusations and have initiated administrative and criminal investigations."

In 2021, following allegations of misconduct within the BRPD’s narcotics division, the police chief fired the officers involved and they were ultimately arrested according to court records.