According to a statement made by associated conspirator
George Atzerodt, discovered long after his death and recorded while he was in federal custody on May 1, 1865, Mudd knew in advance about Booth's plans; Atzerodt was sure the doctor knew, he said, because Booth had "sent (as he told me) liquors and provisions ... about two weeks before the murder to Dr. Mudd's." Although that is true, some historians believe there may have been other reasons behind Mudd's relationship with Booth. The trial brought forth many theories of Mudd's involvement in the assassination of Lincoln. One theory posits that Mudd was involved in a completely different conspiracy to gain an upper hand for the southern states. Prior to killing Lincoln, Booth had intended to kidnap the president and ransom him and other political affiliates of the Union for a large sum of money. This plan was in effect until the night of the assassination, when Booth met up with Atzerodt, David Herold, and
Lewis Powell and disclosed the plot to assassinate the president instead. Booth paid Mudd $25 in
greenbacks for his medical treatment. He and Herold spent between twelve and fifteen hours at Mudd's house. They slept in the front bedroom on the second floor. It is unclear whether Mudd had yet been informed that Booth had killed Lincoln. Mudd went to Bryantown during the day on April 15 to run errands; if he had not already heard the news of the assassination from Booth, he certainly learned of it on the trip. He returned home that evening, and accounts differ as to whether Booth and Herold had already left, whether Mudd met them as they were leaving, and whether they left at Mudd's urging and with his assistance. It is certain that Mudd did not immediately contact the authorities. When questioned, he stated that he had not wanted to leave his family alone in the house in case the assassins returned and found him absent and his family unprotected. He waited until Mass the following day,
Easter Sunday, when he asked his second cousin, Dr. George Mudd, a resident of Bryantown, to notify the 13th New York Cavalry in Bryantown, under the command of Lieutenant David Dana. Mudd's delay in contacting the authorities drew suspicion and was a significant factor in tying him to the conspiracy. During his initial investigative interview on April 18, Mudd stated that he had never seen either of the parties before. In his sworn statement of April 22, he told about Booth's visit to Bryantown in November 1864 but then said, "I have never seen Booth since that time to my knowledge until last Saturday morning." Later testimony from
Louis J. Weichmann revealed that Mudd hid his meeting with Booth in Washington in December 1864. In prison, Mudd admitted the Washington meeting and said he ran into Booth by chance during a Christmas shopping trip. Mudd's failure to mention the meeting in his interview with detectives proved to be a big mistake: When Weichmann told the authorities of the meeting, they realized that Mudd had misled them and immediately began to treat him as a suspect, rather than a witness. During the conspiracy trial, Lieutenant Alexander Lovett testified: == Trial ==