Court records show the suspect was on probation before the fatal shooting.
LEAGUE CITY, Texas — A murder charge filed after a woman was found shot to death Monday in League City has renewed attention on earlier allegations involving the same suspect and victim, according to police and court records.
Isaiah Johnson, 38, of Magnolia, is accused of killing Joanna Walton, 37, at the Harbor Walk Apartments on FM 518. Police said Walton was found dead inside a silver Toyota Corolla around 2:25 p.m. Monday. Johnson and Walton shared a son, according to court documents. Walton’s relatives told Eyewitness News that Johnson had harassed her for years after their breakup.
The fatal shooting happened in an apartment parking lot shortly after Walton arrived, according to surveillance footage described in the investigation. Video showed her car moving through the lot after 2 p.m. A red SUV witnesses linked to the suspect then moved from a nearby carport toward where Walton parked. Witnesses later reported hearing gunshots, and one witness told police he saw a man shoot Walton 11 times.
Police said Johnson fled the area in a Hyundai Santa Fe before turning himself in at the Galveston Police Department about two hours later. Officers said Walton had multiple gunshot wounds when first responders reached the car. Investigators have not released all evidence in the case, including whether any weapon was recovered or what Johnson told police after surrendering.
The earlier cases are now part of the broader picture investigators and prosecutors are expected to review. In 2023, police said Johnson tried to shoot Walton, but the gun jammed. Police said he pistol-whipped her instead. Records show he pleaded guilty, served 30 days in jail and received 10 years’ probation. He also was ordered to complete a battering intervention program.
Police said Johnson was accused last July of breaking into Walton’s apartment while still on probation. An affidavit said he sent Walton threatening messages, including one saying he did not want their son to see her again. Records show a warrant for Johnson’s arrest on the burglary charge was issued in August 2025. Police said that warrant was not served until Johnson turned himself in after Monday’s killing.
Johnson appeared in court Tuesday, and his bond was set at $360,000. The pending legal steps include further review by prosecutors, possible grand jury action and future hearings in Galveston County. Police said the investigation remained open as detectives continued gathering records, video and statements.
By Thursday, Walton’s death had become both a murder case and a review of prior warning signs documented in court records. Johnson remained charged, and the next public developments are expected through new filings in Galveston County court.
Author note: Last updated July 2, 2026.