Grab a few minutes on Thursday morning with Robert M. Morgenthau. But don’t be late. There’s a little time open after his two morning meetings, and before one that begins at 12:30. He hoists a legal brief from atop the heap on his desk, which seems to have been transported intact from the one he vacated in 2009 after 35 years as the Manhattan district attorney.

A vintage mess, but a fresh legal brief.

Mr. Morgenthau, 93, and two other prominent former prosecutors are asking the United States Supreme Court to take up the case of William Ernest Kuenzel, who has been on death row in Alabama for 24 years.

Based on the testimony of two witnesses, Mr. Kuenzel was convicted in 1988 of murdering a convenience store clerk. Records that became available only in 2010 revealed that those two witnesses — one of whom admitted that he himself was involved in the murder — actually did not implicate Mr. Kuenzel when they first spoke with the authorities. In fact, they originally gave entirely different accounts from what they testified to at trial, but the defense lawyer was unaware that their stories had changed. So were the jurors.

Mr. Morgenthau learned about the case from Jeffrey Glen, a law partner of his late son-in-law. Their firm, Anderson Kill & Olick, was working on the appeal, along with David Kochman. To Mr. Morgenthau’s disbelief, the case was rejected by federal courts in Alabama, which ruled that the new evidence did not “refute the possibility that the defendant committed the crime.”