 A retired Russian Jewish fruit peddler living at 111 E. Seventh Street, Davidson shot and killed New York gang leader "Big" Jack Zelig while on a Thirteenth Street trolley on October 5, 1912 following an altercation during a card game at a local cafe.It was suggested immediately that Zelig's murder was an attempt to keep him from testifying against Charles Becker in the Rosenthal murder case involving the Lenox Avenue Gang.However, Davidson later turned himself into authorities, telling police that Zelig had attacked him with a blackjack and robbed him, and that revenge for these acts was his motive for killing Zelig.