The US state of Texas has executed its first death row inmate with a single lethal injection of the sedative pentobarbital.
Yokamon Hearn, 33, was convicted for the carjacking and murder of a Dallas stockbroker in 1998.
Hearn is the sixth inmate to be killed this year in Texas, but the first after the state stopped using a cocktail of three lethal drugs for executions.
Death penalty opponents say inmates die more slowly by the single-drug method.
Hearn previously appealed against his sentence, arguing his mental disabilities and inadequate legal advice early in his case meant he should be spared execution.
Hearn did not show any unusual reactions to the drug, according to reports, and was pronounced dead 25 minutes after the pentobarbital was first administered.
When asked if he wanted to make a final statement, he said: "I'd like to tell my family that I love y'all and I wish y'all well. I'm ready."
Before Wednesday's execution, the three drugs used for court-ordered executions in Texas were: thiopental sodium, to sedate the prisoner; pancuronium bromide to paralyse them; and potassium chloride to stop the heart.
Several states introduced the use of pentobarbital in the face of shortages of thiopental sodium, which was pulled off the market in 2010.
The European Union banned European manufacturers from exporting that drug to the US to prevent it being used in executions. Pentobarbital is also covered by the EU ban.
In Texas, the state chose to switch drugs after its supply of pancuronium bromide expired.
Last year, Ohio became the first US state to use pentobarbital only for executions.
Since then, three other states - Arizona, Washington and Idaho - have switched to a single injection of pentobarbital and a total of 11 executions have been carried out using the practice, according to the Death Penalty Information Center.
Separately, the state of Georgia announced on Tuesday that it would immediately switch to using a single injection of pentobarbital in court-ordered executions.