John David Battaglia Jr. was born on August 2, 1955, at a military base in Enterprise, Alabama. He was of Italian descent. As a child, he moved around a lot because of his father's military career. His family lived in different places across the country and even in Germany. Battaglia's father left the military in 1970.

John attended high school in several places, including Oregon and Dumont, New Jersey. He graduated from Dumont High School. After high school, Battaglia went to Fairleigh Dickinson University. He started as a pre-med major, but later changed his major to accounting. In 1976, he dropped out of college at the suggestion of a friend.

Battaglia had some legal trouble in his early life due to illegal drug use. This led him to join the Marines. He served in the military and became a sergeant. After leaving the Marines, he pursued a career as an accountant. He moved to Dallas, Texas, where his father lived. Battaglia attended night classes to become a Certified Public Accountant (CPA) and worked as a model while studying. Eventually, he became a successful accountant.

John had a daughter named Christie from his first marriage to Michelle Ghetti. The marriage had significant problems, including allegations of domestic violence. Ghetti, who was an attorney, even filed for a restraining order against him at one point. After his troubled first marriage, he married Mary Jean Pearle in 1991. They had two daughters together, named Mary Faith and Liberty Mae, who attended local schools in Highland Park, Texas.

However, Battaglia's relationship with Pearl ended in separation in 1999 due to verbal abuse. Despite the issues in his relationships, until that time he had not harmed his daughters. He was known to be affectionate toward them, but his history of violence and anger towards adult women raised concerns. Battaglia remained involved in the lives of his daughters with periodic visits.

On May 2, 2001, John David Battaglia Jr. killed his two daughters, Mary Faith and Liberty Mae. He had been left in charge of the girls by their mother, Mary Jean Pearle, for a planned dinner. Instead of taking them out, Battaglia took them to his apartment in Deep Ellum, Dallas. During the call with Pearle, he asked the girls to ask their mother why she wanted him to go to jail. Faith, who was 9 years old at the time, pleaded with him not to hurt her, crying out, "No, Daddy!" Pearle told the girls to run, but it was too late. Battaglia shot Faith three times and Liberty five times.

After the murders, Battaglia left a message on the girls' answering machine, saying he loved them and called their mother "evil." He then went to a tattoo parlor to get two roses, which represented his daughters, tattooed on his arm. Battaglia was arrested shortly after, having fought with the police during his capture. Authorities discovered multiple firearms at his home and considered the killings a retaliation against Pearle for reporting him for probation violations.

Battaglia's trial began on April 22, 2002. He was found guilty of capital murder in just 19 minutes. The jury sentenced him to death on April 30, 2002. He was held in the Polunsky Unit, where he awaited execution. His ex-wife expressed her anger toward him and later, nearly sixteen years after the murders, witnessed his execution. Battaglia's execution took place by lethal injection on February 1, 2018, at the Huntsville Unit.

In the aftermath of the murders, new laws related to domestic violence and supervised visits were proposed in Texas. Several organizations were formed to help prevent similar tragedies from occurring in the future. Battaglia's case highlighted ongoing concerns about domestic violence and its potential impact on children.