A man who raped and strangled a 10-year-old Kansas girl in 1999 was executed this week, becoming the fifth federal inmate put to death this year.

Keith Nelson received a lethal injection at the federal prison in Terre Haute, Indiana, after a higher court tossed out a previous ruling that the government was required to obtain a prescription for Pentobarbital, the drug used to kill him.

Questions about whether the drug caused pain prior to death had been a focus of appeals for Nelson, 45. He was the second inmate to be executed this week after the Trump administration resumed federal executions after 17 years.

Nelson kidnapped Pamela Butler off a Kansas City street while she was rollerblading in front of her home on Oct. 12, 1999, planning to sexually assault and kill her. After raping her, he strangled her to death with a wire.

Nelson, who displayed no outward signs of pain or distress during the execution, was pronounced dead nine minutes after the injection was administered. He had no final words, the AP reported.

Observers included Cherri West, Butler’s mother.