President Garfield was shot by a deranged office seeker, Charles J. Guiteau, but he was murdered by doctors and surgeons who probed the wounds with unsterilized fingers and instruments. This was long after Joseph Lister had published his work on antisepsis, so they should have known better.
Garfield died a long, lingering death, and the doctors and surgeons were never charged with his murder, but Guiteau was hanged.
Here’s a concert performance of “The Ballad of Guiteau” from John Weidman and Stephen Sondheim’s Assassins. Will Swenson as Charles Guiteau and Ethan Slater as the Balladeer performing The Ballad of Guiteau, as part of the Classic Stage Company’s benefit concert production of Assassins. Recorded at the Stephen Sondheim Theatre on Broadway, May 9, 2022. Sondheim incorporated a poem, “I am going to the Lordy”, written by Guiteau and recited by him on the scaffold, into the lyrics of the song.
Garfield served too short a time in office to do anything substantial.