Alton Telegraph - April 21st, 1865 The assassin of Secretary Seward is believed to be a man named Sattock*, a Maryland rebel. At least six persons were engaged in the conspiracy; four of whom neglected to perform their part. The murderers have probably escaped across the Potomac to Mosby.
*The man who attempted but failed to kill William Seward was Lewis Powell (a/k/a Paine). Powell rode with Mosby towards the end of the war. In fact, Powell was involved in the capture of Captain Blazer and the defeat of his command of 100 men. Blazer's command was especially created to find and capture or kill Mosby. It consisted of 100 men well armed with the best equipment available including carbines. At the first meeting between one of Mosby's companies and Blazer, the Rangers were badly mauled. Mosby was not pleased and coldly told his humiliated Rangers that he should put them "in hoop skirts" and send them into the first Yankee troop he could find! When Blazer was again an issue, Mosby decided to end the matter. He was going to lead the attack against Blazer personally, but was so ill with "a cold" (probably influenza) that he could not do so. So he sent "Dolly" Richards who took on Blazer in open country. All that returned to Sheridan of Blazer's command of 100 was two men; the rest were taken or slain.
Powell is certainly one of the connections between Mosby and the assassination of Lincoln, though he supposedly "deserted" the command, went to Maryland and signed the oath before winding up with Booth. However, there is speculation that Mosby supplied Powell - an intelligent and powerful young man (Mosby's Rangers did not have any mental lightweights!) - to Conrad for a covert operation and that Powell was sent to Maryland where he made contact with Booth and became part of that conspiracy. If that is true, then Mosby would be legally involved in the plot to assassinate the President. Another scenario has Mosby sending prisoners to Richmond under Powell's command and Conrad deciding that the young man would suit his needs. So Powell was "wined and dined" for a period of time in the Capitol and then sent on to Maryland where he was put in contact with Booth. This scenario removes Mosby from the operation and therefore from any legal culpability.
Powell is never reported to have said anything when a prisoner about his former commander although it may be that he could have mitigated his sentence by incriminating Mosby in the plot. Mosby is mentioned vis a vie Powell only to show that Powell was involved with an "immoral and illegal" operation in Virginia rather than being a simple soldier. Whether Powell did not incriminate Mosby because he was too honorable or because he was not asked to do so is unknown.
John Singleton Mosby's involvement (or lack thereof) in the assassination of Abraham Lincoln is a mystery that has, for a long time, remained a matter of conjecture without proof.
