Updated

The attorney for a Fort Worth man set to die for killing a father and his infant son in 1987 says no last-day appeals are likely to try to stop the punishment.

Texas prison officials are to give 61-year-old James Bigby a lethal injection Tuesday evening for fatally shooting 26-year-old Michael Trekell and suffocating Trekell's 4-month-old son Jayson on Christmas Eve 1987 at their Arlington home.

Evidence showed he also killed two other men, believing they along with Trekell were conspiring against him in a workers' compensation case he filed against a former employer. He wasn't tried for those men's killings.

The U.S. Supreme Court in 2015 refused to review Bigby's case, upholding lower-court appeal rejections.

He'd be the fourth inmate executed this year in Texas and sixth nationally.