The captain of the USS ibn Majid and mentor of Cristobal Rios, who in 2390 obeyed a secret order to kill two synthetic envoys and then took his own life.
Captain Alonzo Vandermeer is the commanding officer under whom Cristobal Rios served as first officer. His story is told in the first-season Picard episode Broken Pieces, set nine years after the events it describes.
The ibn Majid made first contact with two visitors who called themselves Jana and Beautiful Flower. Vandermeer reported the meeting and received a black flag directive from Starfleet Security: the envoys were to be killed at once, or the ship would be destroyed with everyone aboard. He carried out the order.
Rios, who loved him like a father, confronted him about it, and Vandermeer confessed and then shot himself with a phaser. Rios concealed what had happened, Starfleet erased the ship from its records, and the experience ended his career. The order had come from Commodore Oh.