A grandmother detained by the Baton Rouge police for mixing two different prescription pills in the same container said officers interrogated and humiliated her in an unmarked “torture warehouse” known as the Brave Cave, according to a lawsuit filed last week.

The woman, Ternell L. Brown, was pulled over by officers on June 10 and “forcibly” transported to the warehouse, where she was stripped and cavity searched, according to the suit, which was filed in the U.S. District Court for the Middle District of Louisiana.

It was unclear from the documents why Ms. Brown, who was with her husband, was pulled over in the first place.

She was held at the warehouse for more than two hours before being released without being charged, according to the suit, which identified the officers as Troy Lawrence Jr. and Matthew Wallace. Another female officer, who was not named, was also involved, according to the complaint.

Officer Lawrence, who was described in court documents as having an “extensive record of injuring members of the public,” resigned on Aug. 29, television station WAFB reported.

He was charged on Thursday with battery in connection with a separate incident on Aug. 8, in which he is accused of using a stun gun on a handcuffed male subject before he could comply with verbal orders, the Baton Rouge Police Department said on Facebook.

The warehouse, run by the Street Crimes Unit of the Baton Rouge Police Department, was closed in recent weeks after allegations similar to those raised by Ms. Brown came to light, according to the documents.

On Friday, the F.B.I. opened a civil rights investigation into the allegations, saying it was based on “allegations that members of the department may have abused their authority.”

In a statement, the Baton Rouge Police Department confirmed the F.B.I. investigation, adding that Murphy J. Paul Jr., the police chief, had met with the F.B.I. and requested its help to “ensure an independent review of these complaints.”

“The Baton Rouge Police Department is committed to addressing these troubling accusations and has initiated administrative and criminal investigations,” the department said, noting that the Street Crimes Unit was “disbanded and reassigned.”

According to Ms. Brown’s lawsuit, the officers switched off their body cameras and searched her without a warrant, probable cause or consent.

“They were not acting as rogue officers when they sexually humiliated Mrs. Brown; rather, they were simply carrying out official BRPD policy,” court records said.

Another lawsuit, filed on Aug. 29 in the same court, said that Officers Lawrence and Wallace, as well as another officer, Joseph Carboni, beat a 21-year-old man so badly that he had to be treated at a hospital for broken bones and other injuries.

The man, Jeremy Lee, was arrested in front of a house in Baton Rouge on Jan. 9 and detained “without reasonable suspicion or probable cause,” according to court records.

Police handcuffed Mr. Lee and forced him down on a street near the house, where they pulled down his pants to search him and, despite Mr. Lee’s insistence that he was being hurt, proceeded to shove and throw him around, according to the complaint.

Officers Lawrence and Wallace, who frequently muted or switched off their body cameras during the interaction, then took Mr. Lee to the “Brave Cave,” where they were joined by Officer Carboni, the court papers said.

The three “repeatedly kicked and punched” Mr. Lee, according to the complaint.

“Mr. Lee’s screams for help and screams in pain could be heard throughout the facility,” court documents said, noting that the officers “laughed at and mocked” him for his pain.

The officers switched off their body cameras before the beating, which left Mr. Lee with a fractured rib and visible damage to his face, according to the documents. Mr. Lee was not charged with any criminal wrongdoing.

Neither the Baton Rouge Police Department nor the Southern States Police Benevolent Association responded to questions about whether or not the officers involved in both Ms. Brown and Mr. Lee’s cases were facing disciplinary actions.

Mr. Lawrence and Officers Carboni and Wallace could not be reached for comment on Sunday night. Mayor Sharon Weston Broome also could not be reached.

According to the lawsuit filed on behalf of Ms. Brown, the “Brave Cave” was not a jail or detention facility but rather a warehouse adopted as the home base of the Street Crimes Unit.

“It is a place where BRPD takes suspects to interrogate them, gather intelligence and attempt to ‘flip’ them to begin cooperating with BRPD,” the complaint states.

In a news conference last month, Chief Paul said he was “aware of the facility” and referred to the warehouse as a “narcotics processing center” but said he had been unaware of its nickname.

The lawsuits follow other allegations of misconduct in the Baton Rouge Police Department, which came under scrutiny in 2016 after the fatal shooting of a 37-year-old Black man, Alton Sterling.

Officers were also found to have violated department policy when they strip-searched a teenager in 2021. The same year, an internal investigation of the department’s narcotics unit led to criminal charges and internal discipline for the officers involved.