WASHINGTON — Not long after he took office as Philadelphia’s district attorney in 1986, Ronald D. Castille made a handwritten note on a subordinate’s memorandum. “Approved to proceed on the death penalty,” Mr. Castille wrote, in neat cursive script, authorizing prosecutors to seek the execution of a young murderer named Terrance Williams.

Later, when Mr. Castille was running for a seat on the Pennsylvania Supreme Court, he said he was reluctant to take a firm public position on the death penalty, fearing it would require his recusal from all capital cases.

“I can certainly say I sent 45 people to death row as district attorney of Philadelphia,” he told a legal newspaper in 1993, adding that voters “sort of get the hint.” Mr. Williams was the first of those 45.

Mr. Castille won the election and served on the State Supreme Court for 21 years, the last seven as chief justice. One of his final acts, about two weeks before he retired at the end of 2014, was to join a unanimous decision reinstating Mr. Williams’s death sentence.