He was born in 1841 and had two brothers: Florence Scannell who was killed in 1869 in a bar-room fight; and Edward A. Scannell, who on Christmas Eve of 1875 killed a man named Henry Wilson, in what appeared to be a random attack.[1][2] However, John J. Scannell had already shot and killed Thomas Donahue in revenge for the killing of his brother in 1872.[3] He was arrested and was acquitted on the grounds of emotional insanity.[1] While he was imprisoned in The Tombs, he met Richard Croker, the future head of Tammany Hall and they developed a friendship. Croker was at the time also imprisoned and charged with murder, for which he was found innocent.[4]
^"A Man Deliberately Hunted to Death. Thomas Donoghue Murdered by John Scannell. Flight and Capture of the Assassin. An Angry Mob Endeavor to Lynch Him". Chicago Tribune. November 6, 1872. The Scannell-Donoghue feud culminated last night in the murder of Thomas Donoghue by John Scannell, brother of Florence Scannell, who was shot several years ago in a bar-room fight. The result of this most bitter feud was not unexpected, as Donoghue was known to be in constant danger of his life at the hands of Scannell, who succeeded in shooting him last...
^"Mr. Scannell's $35,000 Bag. Fortune in a Grip He Left Behind to Catch a Train to Saratoga". New York Times. June 28, 1902. Retrieved 2010-03-24. John J. Scannell, the Tammany politician who recently bought a stock farm here, pays occasional visits to inspect the many improvements he is making on the property. He made one of those visits yesterday, and paid a hurried call to his newly acquired farm, which includes a well-laid half-mile track.
^"John J. Scannel Buys Saratoga Land". New York Times. July 10, 1902. Retrieved 2010-03-24. Ex-Fire Commissioner John J. Scannell of New York, owns Chateau Ophelia, one of the finest country places about Saratoga, has purchased a lot of land on Clark Street ... for $53,000.