A mentally ill woman committed suicide by shooting herself in the head with an Illinois police officer's gun on Wednesday, according to local TV station KSDK.

Stephanie Hicks, 20, got into a struggle with an Alton police officer who was giving her a ride to a local hospital in his squad car. Hicks, who suffered from bi-polar disorder, managed to unsnap the officer's holster, get a hold of his weapon and turn the gun on herself, the Daily Mail reports.

Hicks and her former boyfriend, Eric Perry, got into an argument that morning, which prompted Perry to call the police. He told cops that Hicks planned to walk from her home to a hospital in St. Louis -- a nine-and-a-half mile distance -- in 105-degree weather. At around 9 a.m. an officer spotted Hicks on a bridge.

The officer contacted an EMS crew, who determined that Hicks was not suicidal. But she was determined to get to the hospital to seek professional help for her mental illness.

“She was adamant about going to St. Louis,” Alton Police Chief David Hayes told KTVI's FOX2. “So [instead of] allowing her to walk nine-and-a-half miles, our officer asked permission to provide her courtesy transportation to Christian Hospital, which we don’t normally do.”

Hicks accepted the "courtesy ride" from the officer, who claimed that Hicks "never said a word" while she rode in the patrol car, according to St. Louis Today.

Since she was not in custody, Hicks was allowed to sit in the front passenger seat.

“She was not a threat," Hayes said to CBS St. Louis.

"She’s a five foot, one hundred-pound girl, and nobody in their right mind would perceive a person like that to be a threat,” he told FOX2.

On the way to the hospital, Hicks unsnapped the officer's gun from his right hip holster and shot herself in the head. She was then taken to Barnes-Jewish Hospital in St. Louis, where she died.

Robbin Hicks does not believe that her daughter could have wrestled a weapon from a police officer.

“There’s no way she should have got that gun,” she told FOX2. “I’m angry and I’m pissed and this is not right.”

Hicks's grandmother, Joan Singleton, agreed.

“How did that little girl get that gun?” she asked. “Tell me how she could just get a gun from a police officer?”

The patrol car is equipped with a video camera, which is linked to the vehicle's emergency lights. Because the emergency lights were not turned on until after the gun was fired, the camera did not capture any footage of the actual incident.

The officer, a 13-year veteran of the force, is on administrative leave pending an internal affairs investigation by the Alton Police Department.