Mental health patient who killed Dallas doctor mistakenly released from jail

Dallas police have re-arrested a mental health patient who killed his doctor over the summer. He was released from jail by mistake.

Surveillance video shows 55-year-old Tony Cason attacking Dr. Ruth Mardock at Timberlawn Mental Health Systems, a psychiatric hospital in Dallas, on June 30.

Dr. Mardock hit her head on the ground during the attack and died from her injuries two days later.

Cason was arrested at the scene. He was being held in the Dallas County Jail for manslaughter but was released on Aug. 19 for some reason.

In a statement, the Dallas County District Attorney’s office said it was not involved in his release and the sheriff’s department is now investigating how and why that happened. The county's criminal justice director said it does indeed appear to be a case of human error.

After his release, Cason called his attorney, who is on vacation, and left a message asking what was going on.

Dallas police started looking for Cason after the mistake was discovered Wednesday. A judge confirmed police located him Thursday morning and is back in custody.

Sheriff Lupe Valdez said it was the media who first informed her office about Cason's release. She said it's too soon to know who or what caused this admittedly huge oversight.

"We're just so blessed and lucky that he didn't go out and commit a violent crime," she said. "So we're very aware that whatever the error is that we need to take care of it."

Attorney Pete Schulte, who is not associated with this case, says the system needs to be set up to prevent human error.

“I understand people are going to make mistakes,” he said. “But when we’re talking about jail where someone can be released and there be catastrophic consequences, there's got to be double checking going on before someone, especially charged with murder, is released from jail.”

Sheriff Valdez said this is the first time that she can recall, under her leadership, that an inmate has been mistakenly released under these circumstances.

If it does indeed turn out to be a case of human error, Valdez promises due process and swift action.