Captain Patrick D. Tyrrell (c.1831–April 3, 1920) was an Irish American detective of the United States Secret Service who, as head of the field office in Chicago, became involved in foiling a plot to steal the remains of President Abraham Lincoln on November 7, 1876.
After a hunt that lasted eight months across five states, Tyrrell and his agents captured Boyd and his wife Almiranda in Fulton, Illinois on October 21, 1875; Chief Washburn apprehended Driggs in Centralia that same day.
In that meeting, Tyrrell explained all the details he had of the plot and requested that he allow the crime to go forward in order to catch the criminals in the act; after initial hesitation, Robert Lincoln agreed.
[8][9] Tyrrell then recruited a group of Secret Service agents and Pinkerton detectives to assist him in stopping the plot and apprehending the grave robbers.
On the evening of November 7, while Mullen and Hughes made their move on the tomb, Tyrrell, Power, and his agents were waiting in the vestibule for Swegles to signal them; fearful of the echoes on the marble floor as they paced, they had removed their boots.
[6] Finally, Swegles gave the pre-arranged code word, "wash", and the agents moved in, but one of the Pinkertons accidentally discharged his pistol, causing the robbers to make a hasty retreat.