Among those sentenced were Brig. Adm. Ibrahim Yildiz and Col. Hakan Biyik, who had admitted to ties with Mr. Gulen’s movement and served as secret witnesses during earlier hearings. Both men received sentences of 16 years and eight months, even after their cooperation with prosecutors was taken into account. Their testimony forms a key part of the extradition request that Turkish prosecutors have submitted to the United States. The Treasury Department is examining that request.

Colonel Biyik told prosecutors that he had been at meetings to plan the overthrow in a villa in Ankara, according to Turkish news reports. He identified some of those present and said the meetings, called the Peace at Home Council, were organized by a theology lecturer, Adil Oksuz, who has been accused of playing a leading role in the coup attempt and remains at large. Prosecutors said they had found fingerprints in the villa of some of those he had named, the newspaper Haberturk reported.

Admiral Yildiz has emerged as one of the most important witnesses of preparations for the failed coup. He also attended the meetings in Ankara and, according to the indictment, testified that at one, Mr. Oksuz had announced that he would take the plan to Mr. Gulen for his approval and that he had traveled to see Mr. Gulen in Pennsylvania three days before the coup, according to Hurriyet.

Admiral Yildiz took part in the plot but gave himself up before the attempted ouster of the president was foiled.

“I am one of the first people who testified that Gulen was behind the coup,” he said in court in March, the news agency Anadolu reported. He said he had been introduced to the Gulen movement by a fellow officer and had been drawn closer to it because of his Muslim faith, but he added that he had ultimately been deceived.

“I am just an Anatolian boy who became an admiral,” he told the court. “I want you to accept me as someone who is not trying to avoid a sentence but whose religious sentiments were abused and cheated by them.”