A man already closed on a capital murder charged in his grandmother’s death now faces additional charges after allegedly killing his cellmate at Harris County Jail.

Authorities say Chad Maydwell fatally attacked Michael Griego, an inmate jailed for aggravated assault on a family member, on Nov. 12, 2022.

It’s unclear what led to the murderous altercation, but court documents allege Maydwell used his hands and feet as deadly weapons, striking Griego multiple times in the head, face, neck and torso. He also apparently threw Griego from an upper bed onto the floor.

BACKGROUND: Bond set at $1 million for man accused of killing 80-year-old grandmother in NW Harris County, documents show

Griego, who is awaiting trial, was pronounced dead as a result of the assault.

Maydwell was already in prison, charged with capital murder for the brutal the killing of his 80-year-old grandmother, Judith Ellen Maydwellin April 2022.

According to court documents, Maydwell killed his grandmother in her northwest Harris County home using a blunt object or his hands after breaking into her residence. Authorities later found Judith Maydwell’s body during a welfare check requested by her daughter.

Neighbors reported seeing Chad Maydwell’s vehicle at the scene prior to the murder. Investigators say he also fled after the murder, but was captured by a Harris County K-9 Unit with help from Texas DPS and later confessed to the killing while being treated by EMS.

At the time of his grandmother’s murder, Maydwell was on bail for indecent exposure. He also had a lengthy criminal history dating back to 2009, including charges of criminal trespass, assault and resisting arrest.