Ronald Davis, 37, who is married and has a family, claimed she was suicidal based on text messages he had received and obtained a document to commit her on 21 August in the US state of Pennsylvania.

He allegedly used the document to restrain her without getting sign-off from his supervisor and did not wait for another officer to accompany him, taking an "acquaintance" instead.

Davis has been charged with strangulation, unlawful restraint, false imprisonment, simple assault, official oppression and recklessly endangering another person and is in Dauphin County Jail.

Footage of the incident released by the Dauphin County District Attorney's office shows Davis on top of the woman, who asks him "what is wrong with you?", adding: "I don't need help, I need to get away from you."

After a few minutes on the ground, he then bends her over the back of a car, before another struggle ensues.

She was committed to a psychiatric facility based on an Involuntary Mental Health Commitment from 21 August until 25 August, according to a police affidavit.

Davis's lawyer, Jay Nigrini, said he has been denied bail.

"We are confident once all of the facts come to light, Mr Davis committed no crime, but was seeking to protect a troubled young woman who was in need of immediate medical attention," he added.

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According to the charging documents, Davis did not explain why he was restraining the woman.

They also claimed the text messages used to obtain the documents were part of a larger context that "revealed her frustration with Trooper Davis and his controlling behaviour" and "not a true desire to harm herself".

During the text exchange, Davis wrote: "Go f*** yourself. You're done. F*** around and find out."

The woman claims Davis told her during their relationship "I know you're not crazy" but that he will "paint you as crazy" and that he "knows the law".

The police affidavit states: "After reviewing the text messages, your affiants were not able to identify any suicidal or homicidal threats or ideations."

A spokesperson for Pennsylvania State Police said he has been suspended without pay.