HUNTSVILLE, Texas — The Texas Court of Criminal Appeals on Friday halted the execution scheduled for later this month of a man convicted of killing a Houston police officer 28 years ago.

Robert Jennings, 58, was set for lethal injection Sept. 14 for fatally shooting Elston Howard, a Houston police vice officer, at an adult bookstore in Houston in July 1988.

It’s the fourth execution stopped by the state’s highest criminal appeals court over the past month. Different issues were raised in each case.

The brief five-paragraph order from the court indicates four of the panel’s nine judges opposed the reprieve for Jennings. The court offered no reason for stopping the punishment, saying only that it should be halted “pending further order of this court.”

Attorneys for Jennings are questioning in an appeal before the court whether jury instructions during the punishment phase of his trial were proper, arguing jurors couldn’t adequately consider Jennings’ remorse about the killing when they were deliberating punishment. At the time of his trial in 1989, rules covering capital trials were evolving in the state and federal courts.

Howard’s shooting occurred more than two months after Jennings was paroled after serving about 10 years of a 30-year sentence for robbery. Witnesses said the 24-year-old officer was arresting a bookstore clerk for showing movies without a license when Jennings walked in and opened fire, shooting him in the arm and neck. After a struggle that ended when Howard became unconscious, witnesses said he shot Howard again in the head.

Jennings was arrested later that day. Evidence showed he was responsible for 10 robberies after getting out of prison.

Fifteen convicted killers have been executed so far this year nationally, with Texas and Georgia the most active with six executions each. At least four more Texas inmates have lethal injections scheduled in the coming months.