Suspect wanted on probation violation prior to murder of woman in League City, arrest warrant shows

LEAGUE CITY, Texas (KTRK) -- A man accused of killing a woman in League City was on probation for attacking her years ago, then was accused of breaking into her apartment while still on probation, according to court records.

An arrest warrant was issued nearly a year ago, but it was never served, according to court records.

The League City Police Department said Isaiah Johnson turned himself in just hours after shooting and killing Joanna Walton on Monday.

Police said Walton was found dead inside her car at her apartment complex.

About two hours later, officials said her ex-boyfriend and the father of their child, Johnson, turned himself in.

Walton's family told ABC13 this wasn't a random act of violence, but instead followed years of alleged abuse and harassment after the couple split.

Court records obtained by ABC13 detailed the troubling history.

In 2023, police said Johnson pleaded guilty to aggravated assault with a deadly weapon after allegedly trying to shoot Walton, but pistol-whipped her instead after the gun jammed.

He was sentenced to 30 days in jail and 10 years' probation, according to court records.

While still on probation, police said Johnson broke into Walton's apartment, and police issued an arrest warrant for burglary in August 2025.

But records show the warrant wasn't served until Johnson turned himself in Monday on the murder charge.

It isn't clear whether law enforcement attempted to arrest Johnson on the burglary warrant.

ABC13 reached out to the League City Police Department about that, which was the lead agency on the case.

We're still waiting to hear back.

Regarding Johnson's probation, court records show it was transferred to Harris County.

But the county's Community Supervision and Corrections Department told ABC13 they never received the arrest warrant for the burglary.

ABC13 went to the Galveston County DA's office, which filed that arrest warrant.

When asked if they ever notified Harris County of Johnson's warrant, they said, "No comment."

As for Johnson, jail records show he is in jail with a bond set at $360,000.