Ken Thompson, the Brooklyn district attorney, dropped a memorable line at the end of his letter this week recommending no prison time for Peter Liang, the former New York City police officer convicted of manslaughter last month in the fatal shooting of an unarmed man in a housing project stairwell.

“There are no winners here,” he wrote.

Mr. Thompson was referring primarily to the two chief players in the tragic drama: Mr. Liang’s victim, Akai Gurley — “a completely innocent man who lost his life for no reason” — and Mr. Liang himself, who has already lost his job and who stands to lose his freedom when he is sentenced next month.

But along the way the case has had winners, and losers, though it has at times been hard to tell them apart. When Mr. Thompson’s letter was released on Wednesday, Mr. Gurley’s family and criminal-justice reform activists expressed outrage, just several weeks after having applauded Mr. Liang’s conviction, and before that his indictment. In a stark but mirroring contrast, the city’s police unions and many in its Chinese-American community denounced the indictment and conviction, but they are now praising prosecutors and cheering the prospect that Mr. Liang, who is of Chinese heritage, might avoid prison.

If the best settlements are those in which each side leaves unhappy, then it could be that Mr. Thompson has himself emerged a winner, if a battered one, near the end of the sort of polarizing police misconduct case that can define a district attorney’s career. A first-term prosecutor with electoral potential, he had much to lose by even pursuing the case, which was fraught from the start with legal hurdles and political pitfalls.