CHICAGO, United States (AFP) — A US inmate was scheduled to be executed in Texas Tuesday for murdering his girlfriend while he was on parole for the murder of his wife.

William Rayford’s attorneys filed last-minute appeals, asking the Supreme Court and a federal judge in Texas to halt the execution on multiple grounds.

The 64-year-old killed his girlfriend Carol Lynn Thomas Hall in 1999, after an argument the two had in her home.

At the time, Rayford was on parole, having served eight years of a 23-year sentence for the 1986 murder of his estranged wife Gail Ann Rayford.

Both killings were brutal attacks that occurred in front of the women’s children. Hall’s body was found beaten, strangled and stabbed.

Hall’s then 11-year-old son was also beaten and stabbed when he tried to stop the attack. He survived and was a witness in Rayford’s trial.

Rayford’s attorneys have asked the US Supreme Court to halt the execution, alleging the convict, who is black, had insufficient representation and that his initial sentencing may be marred by race-based prejudice.

In another pending appeal, they claimed recent tests showed Rayford suffered decades-long brain damage caused by lead poisoning from bullets and bullet fragments lodged in his body, and from contaminated water.

If carried out, the execution would be only the second in the country, after Texas put to death Anthony Shore two weeks ago. Texas is scheduled to execute another inmate on Thursday.

The number of executions in the US declined to a near-historic low of 23 last year, according to the Death Penalty Information Centre.