Yes, he was pardoned for his good behavior and the use of his medical skill in the fever epidemic. From all accounts I've read, he was a model prisoner there were no complaints about him. Even so, just 4 years after the death of Lincoln, one who was sentenced to life because they were convicted of being part of the plot to kill Lincoln is given a pardon? Given the Martail Law and the other punishment given the South because there were Union officers and others in government who still believed the South had a hand in it that lasted well over four years, it's just a stretch for me to understand his pardon due to the crime he was convicted of. One vote short of the gallows. Four years later, going home. I don't know for sure if he had any knowledge of anything, I really want to think he was just doing his best as a Dr when Booth came to call. I want to know why Johnson thought it was ok to pardon the man who was convicted as part of the group who killed his predecessor.
See how easy it is for one story, even an old one to take on a life of it's own? Wonder if there's still going to be conspiracy theories and stuff on JFK and Lincoln 100 years from now?