It was one such vigilante group that swarmed Alimuddin Ansari, a Muslim trader, in Mr. Sinha’s constituency last year. A rumor spread that Mr. Ansari was transporting beef, and a mob dragged him out of his van and beat him. Police officers eventually pulled him away, but he died a few hours later from internal injuries, officials said.

His family is now broke.

“My life is doomed,” said Mariam Khatoon, his widow. She sat in a plastic chair in a ramshackle house, the concrete foundation cracking beneath her feet.

From cellphone footage — some gleefully shot pictures of themselves hitting Mr. Ansari — investigators identified 12 suspects and a court sentenced all of them except a juvenile to life in prison.

But a higher court recently granted an appeal, saying the evidence was flimsy. Upon their release on bail, eight of the men went to visit Mr. Sinha at his house, where he was waiting with wreaths of marigolds.

There is still doubt about the circumstances of Mr. Ansari’s death. A lawyer representing some of the convicted men said that, yes, the mob had roughed up Mr. Ansari but that it was actually police officers who beat him to death, in custody. The lawyer pointed to photos that have been circulating on social media that show Mr. Ansari looking alert and apparently not badly injured as officers led him away from the mob. The trial court had heard many of these arguments and rejected them.

Mr. Sinha said he was helping the convicts because there was “no evidence” that they killed Mr. Ansari. He has actively supported their legal defense, paying several hundred dollars to one of the defense lawyers and connecting this lawyer to an experienced attorney friend to craft a persuasive appeal.