A physician at Dallas’ Timberlawn Mental Health System who was attacked by an upset patient Thursday has died.

Tony Cason, a patient at Timberlawn, was angry after learning on June 30 that he would be transferred to a different facility for treatment, according to an arrest warrant affidavit.

He attacked Ruth Mardock outside his hospital room as a result.

“Suspect Cason violently tackled complainant Mardock to the ground,” the affidavit reads. “Mardock struck her head on the ground and lost consciousness.”

The attack was captured on surveillance video, which has not been made public.

It was determined Friday that Mardock would not recover from the attack. She died Saturday.

Cason was initially arrested for aggravated assault causing serious bodily injury. He now faces a manslaughter charge, according to jail records.

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<p>Tony Cason. Credit: Dallas County Jail</p>

Timberlawn Mental Health System is located at 4600 Samuell Boulevard in eastern Dallas. The facility "offers comprehensive care for adults who are struggling with psychiatric issues or have a history of trauma," according to its website.