The Georgia Bureau of Investigations is looking into the mysterious death of a woman who passed away after falling out of a moving police car on Thursday (July 21).

Brianna Grier died following an “in-custody incident with Hancock County Sheriff’s Office deputies.” Mary Grier, Brianna’s mother, called the police for help after the 28-year-old suffered from a schizophrenic episode on July 15. This is not the first time law enforcement was called to assist with Brianna’s mental health episode, but the sheriffs didn’t contact medical help as they’ve done in the past. Cops reportedly handcuffed her for intoxication without a proper assessment.

Brianna’s father, Marvin Grier, told The Daily Beast, “They told her they were going to detain her until the next morning when they would come up and do a 10-13 – that is to take her to a facility…to get someone to come get her from the police department to get her some help. But she never made it there.” The family told the outlet that they weren’t notified about Brianna’s condition until the following day, and she was checked into the hospital under an alias.

Brianna’s sister, Lottie Grier, told the outlet her brother unsuccessfully attempted to visit her after learning she was hospitalized at Grady Memorial. Lottie said, “They had already told him that she was there, but another nurse came in to say they weren’t supposed to know she was there because she was up on an alias.” Lottie continued, “They made it seem as if she was stable, but we just couldn’t see her.” But two days later, Brianna’s family received a call saying she sustained multiple head injuries and died as a result. “They didn’t even have a contact for you know her family, next of kin or whatever, they said they had to look her up on Facebook,” she said.

The GBI stated, “Grier was arrested at home. While deputies were taking Grier to the Hancock County Sheriff’s Office, Grier fell out of a patrol car and sustained significant injuries. She later died because of those injuries.” Grier’s father claims she was airlifted to a hospital after fracturing her head. She remained in a coma for days and was taken off a ventilator after medical professionals declared Grier “brain dead.” Mary told WMAZ, “If she got out [of] the car, they had to let her out [of] the car.” She continued, “That’s my interpretation, because in a police car, you can’t open the door from the inside, it had to be the outside.”

A professor of criminal justice at the University of South Carolina confirmed to NBC News that police cars are always supposed to be locked from the inside. Geoffrey Alpert told reporters, “Otherwise, prisoners would be letting themselves out all the time.”