On Election Day, October 10, 1871, Catto was teaching in Philadelphia. Fights broke out in the city between black and white voters, as the elections were high in tension and parties reflected racial opposition. Black voters, who were mostly Republican, faced intimidation and violence from white voters, especially ethnic Irish, who were partisans of the city's Democratic machine. Irish immigrants had entered the city in great numbers during and after the Great Famine of the 1840s; they competed with free blacks for jobs and housing. City police were called on to quell the violence. Instead, often ethnic Irish themselves, they exacerbated the problems, using their power to prevent black citizens from voting. A Lieutenant Haggerty was later arrested for having encouraged police under his command to keep African Americans from voting.[1]
On his way to vote, Catto was intermittently harassed by whites. Police reports indicate that he had purchased a revolver for protection. At the intersection of Ninth and South streets, Catto was accosted by Frank Kelly, an ethnic Irish man, who shot him three times. Catto died of his wounds. The city inquest was not able to determine if Catto had pulled his own gun. Kelly was not convicted of assault or murder.