Jury hears of woman’s grave under house at Fort Worth death penalty trial
Mascara ran down Marissa Grimes’ face at a house in the Como section of west Fort Worth.
Valerian O’Steen was furious with Grimes, with whom he was in an intimate relationship, a neighbor who says he observed the flare of anger will testify in O’Steen’s capital murder trial in Grimes’ killing.
Assistant Criminal District Attorney Peter Gieseking on Tuesday previewed the state’s case in his opening statement as he and another prosecutor began presenting evidence to a jury in the 371st District Court in Tarrant County.
The Tarrant County Criminal District Attorney’s Office is seeking the death penalty.
The neighbor recalls O’Steen waving a pistol during the encounter in January 2022, Gieseking said.
“You’re going to get this leg monitor off me,” O’Steen said, according to the expected testimony of the neighbor who says he heard the statement, Gieseking forecast.
In the month before Grimes was killed, she accused O’Steen of pointing a gun at her head, and Fort Worth police arrested him on suspicion of two offenses. O’Steen was released the next day after a magistrate set his bond at $15,000. A GPS leg monitor was among O’Steen’s bond conditions.
Prosecutors allege that O’Steen was in the course of committing or attempting to commit obstruction or retaliation when he beat Grimes to death.
A crime scene unit officer and medical examiner’s office investigator will describe to the jury sawing open the floor to expose Grimes’ grave underneath O’Steen’s house, Gieseking suggested in his opening statement. Her body was covered by blankets, tarps and dirt.
O’Steen is accused of beating to death Grimes, who was 26 and the mother of three young children.
In the days before police found Grimes’ U-Haul vehicle abandoned on Lake Como Drive, her relatives reported that she was missing. The vehicle was about a mile from O’Steen’s house on Locke Avenue, according to the account of a homicide detective that is included in an affidavit supporting O’Steen’s arrest warrant.
On Feb. 22, 2022, police executed a search warrant at O’Steen’s house and found a crawl space entry in a bedroom closet. A SWAT officer looked down into the space and saw a mound of dirt and smelled the odor of decomposition. The next day, police found Grimes’ body in the crawl space.
A Tarrant County Medical Examiner’s Office pathologist determined that her death was a homicide caused by blunt force trauma to the head.
O’Steen, who is 27, is the second capital murder defendant for whom the state decided to seek the death penalty to go to trial in Tarrant County this year.
A jury in May found Lamont Cousins guilty of capital murder in killings in December 2020 and assessed his punishment as life in prison without eligibility for parole. Juries in Tarrant County last year sent three defendants to death row.
If a jury finds O’Steen guilty of capital murder, it would hear evidence in a second trial phase and consider two options: life in prison without eligibility for parole, or the death penalty.
In the punishment phase, jurors would weigh whether the state proved beyond a reasonable doubt that it is probable that O’Steen would commit future criminal acts of violence that would constitute a continuing threat to society. The panel also would weigh whether there was mitigating evidence that it might regard as reducing O’Steen’s moral blameworthiness and warrant a sentence of life in prison without parole.
Defense attorneys Bob Gill, Miles Brissette and Colin McLaughlin were appointed to represent O’Steen. The defense on Tuesday reserved its option to address the jury in an opening statement later in the trial.
Judge Ryan Hill is presiding.
Gieseking represents the state in the case with Deputy Criminal Division Chief Allenna Bangs.
This story was originally published August 12, 2025 at 5:41 PM.
