President James Garfield was in office only four months when (Spoiler Alert!) he was shot by Charles Guiteau in 1881, and died of his wounds shortly thereafter. This American Experience spends two hours on this presidential cold case, even though the assailant is unassailably identified – perhaps because this story, as American assassinations go, is so little-known. But I recommend finding, hearing and watching the TV version of Assassins, the Stephen Sondheim musical that gathered all such cases into one astoundingly bold and brilliant story. Playing the wacky yet dangerous Guiteau, when I saw the revival on Broadway, was Denis O’Hare, whose singing of Guiteau’s actual gallows-day song, “I Am Going to the Lordy,” was a stunningly powerful performance. So were those by Michael Cerveris as John Wilkes Booth and Neil Patrick Harris as Lee Harvey Oswald, among others. Really worth seeking out. Check local listings.