Nathaniel Mitchell (Tarrant County Corrections Center)

An estranged boyfriend is suspected in the slaying of Donna Alexander, who grabbed national headlines when she created the Anger Room in Deep Ellum, a warehouse designed to help people cope with stress.

Nathaniel Mitchell, 34, was charged with murder after Alexander died a week after being beaten.

Alexander's business allowed visitors to smash things for a fee as a way to relieve stress.

"I always wanted to be able to relate to what people are angry about," Alexander said in a 2016 interview with The Dallas Morning News. "Most people have stress from work or home-related issues."

Alexander was attacked in her Grand Prairie home and taken to Baylor University Medical Center in Dallas on Sept. 21 with severe injuries, Grand Prairie police said.

Mitchell, who took Alexander to the hospital, gave staff a story they found to be inconsistent with her injuries, officer Mark Beseda said. Officers interviewed Mitchell and arrested him at the hospital on outstanding warrants.

He was initially charged with aggravated assault, but the charge was upgraded to murder when Alexander died of her injuries Aug. 24. Mitchell is being held in the Tarrant County Corrections Center in lieu of $250,000 bail.

A vigil for Alexander is scheduled for 6 p.m. Monday at Cole Park in Dallas.