HUNTSVILLE, Texas — A Texas prisoner was executed Tuesday for the shotgun slaying of a Dallas-area liquor store clerk during a robbery more than 25 years ago.

Gustavo Garcia, 43, was pronounced dead at 6:26 p.m. — 16 minutes after the drug began to flow. His lethal injection was the third this year in Texas, which carries out capital punishment more than any other state.

‘‘God bless you. Stay strong. I’m done,’’ Garcia said in his final statement, adding that he loved his mother and other family.

As the lethal dose of pentobarbital began taking effect, he yawned, gurgled, exhaled, and began quietly snoring. Within 30 seconds, all movement stopped.

Garcia was sentenced to death for fatally shooting 43-year-old Craig Turski during a 1990 holdup in Plano. It was one of two killings during robberies linked to Garcia, who was 18 at the time, and then-15-year-old Christopher Vargas.

Garcia’s attorneys made no late legal attempts to stop the execution after the US Supreme Court’s refusal last week to rehear an appeal. The Texas parole board refused a clemency petition.

Garcia spent more than half of his life on death row for the killing of Turski. Vargas was tried and convicted as an adult and sentenced to life in prison. His young age made him ineligible for the death penalty.

Court documents show Garcia shot Turski in the abdomen on Dec. 9, 1990, then reloaded and shot the man in the back of the head. A month later, Garcia and Vargas entered a Plano convenience store armed with a sawed-off shotgun and carried out a holdup in which another clerk, 18-year-old Gregory Martin, was fatally shot in the head.

Associated Press