Jack Walters was born in 1890, the youngest of three children. He grew up in Boston, Massachusetts. He underwent a disruptive upbringing due to the excessive alcohol and gambling habits of his father. Young Jack was often beaten by his increasingly violent father, who eventually killed himself. His mother was forced to work long hours to support the family financially, and eventually died prematurely in 1901.

Jack was eventually taken into foster care, joining the Police force a few years later after falsifying his age on his application.