I'm currently reading a biography of Chester Arthur and while I knew the general outline of Garfield's assassination and Charles Guiteau was a disgruntled office seeker, but I didn't really know that much more. What I found interesting was that Guiteau wanted Arthur to be president as he felt then he'd get his position. This really looked bad for Arthur until it was realized just how crazy Guiteau was and that he wasn't involved with any other group.
The other neat "factoid" here is that Alexander Graham Bell tried to use his induction balance to find the bullet! There are various arguments that this might have worked had Garfield not been on a metal mattress, but honestly, let's face it - 1880s medicine killed Garfield! We can see similar things about McKinley, even Harding!
Anyway, here is some information on the use the induction balance:
While in Boston, Alexander Graham Bell (father modern day telecommunications applications like cell phones and answering services) read the newspaper account mentioned in the above paragraph of this article. Upon reading this account, Bell telegraphed Newcomb in Baltimore and offered to assist him. Further, he suggested that perhaps his own invention of the telephone was the answer he had been seeking. His telephone amplified sound made through wire!
Newcomb accepted Bell's offer. Bell immediately went to Baltimore to work with Newcomb. White House surgeons spent a lot of time at the Baltimore lab witnessing the experiments. The invention consisted of two coils of insulated wire, a battery, a circuit breaker, and Bells' telephone. The ends of the primary coil were connected to a battery and those of the secondary coil were fastened to posts of the telephone. When a piece of metal was placed in the spot where the circuit breaker was, a hum could be heard in the telephone receiver. As the metal was moved further away, the hum became more faint. Five inches away was the maximum distance that a hum could still be heard.
Various methods of testing the apparatus were tried. At first a game of hide and seek was played. Either Bell or Newcomb would hide an unspent bullet in their mouth, arm pit, or elsewhere on their body. The other would pass the wand over the others' body. Meanwhile an assistant would be listening on the telephone to announce (based on the hum) where the bullet was and how far away from the tip of the wand it was.
Next, the experiments included spent bullets and hiding them in bags of grain, inside sides of beef and so forth. Various adjustments were made with each test.
As a final test, before using it on the president, they went to the Old Soldiers Home in Washington, D.C. where they solicited Civil War veterans and lined them up in open fields. They passed the wand over each volunteer's body. As some still had bullets in their body from doing battle in the war, this provided a very close approximation of what they hoped their invention would accomplish -- locate a bullet inside a human body. In each case, the soldiers with bullets still in them, and where the bullets were, were identified. Now was the appropriate time to try the invention on the president. On July 26, Bell, his assistant Tainter, and Newcomb had an appointment at the White House. In the early evening they made their first attempt to locate the bullet using their apparatus. There were also five White House doctors and several aides present for this experiment. The president looked apprehensive as the wand was passed over his body. He expressed a fear of being electrocuted. Bell offered reassurance and tried to explain how the apparatus worked. None-the-less, Garfield's eyes never left the wand through out the experiment.