"My brother's problems started over 30 years ago before he was born, because he was born to a father who was an alcoholic and a mother who had mental problems and nervous breakdowns," his sister wrote.
Zagarella's family could not be reached. But in one of the letters, his uncle said that as a child, he had been verbally abused by his mother who "took out on him the anger and contempt she felt for her husband." She sent him to a boarding school and never visited, several relatives recount in the letters.
His father was the only one who had a somewhat constant presence in his life; yet, he was ill, too. "His father brought him to the bars with him and taught him the life that would haunt him forever," his then-girlfriend, Donna Keahon, wrote the judge.
At 17, Zagarella entered the Army and appeared to be "flourishing," Keahon, said, but when his father became ill and asked him to come home, Zagarella complied.
"Being that Philip loved his father he returned home and was mortified by what he saw," Keahon recounted. He tried to get his father help, but the father refused and instead encouraged him to join him in drinking. she said in the letter.
"So Philip stayed with his father, and gave up on his own dreams," Keahon wrote.
As his father lay on his death bed, "hallucinating from alcohol poisoning, told Philip he was a worthless son," his uncle, James Gulezian, wrote.
What followed was a number of encounters with the law.
He was first convicted of criminal possession of a weapon in the third degree and sentenced to a year in jail. Later, he was charged with attempted murder and pled guilty to assault, after stabbing a man "three to four times," court documents state. "The man lost his kidney, and damage to his spleen and to his liver."
In her letter, his sister stated that in that incident, he had nearly killed a neighbor in a fit of drinking and jealousy over the man's "close relationship with his family ... His problem is the lack of love in his life, which he wanted and needed."
In 1986, Zagarella started making suicidal threats and struggled again with drinking. The following year, he pleaded guilty to entering the home of his girlfriend's estranged husband with a handgun and a sawed-off shotgun.
As Zagarella faced a third conviction, his family reflected on the need for help -- a help they didn't know how to give.
"We didn't understand his cries," his sister wrote back then. "Oh, I wish I had."
In 1998, he was arrested for domestic violence, after allegedly hitting his wife as she tried to prevent him from getting in a car after drinking.
Pastor Jimmy Jack of Teen Challenge in Amityville said Zagarella and his wife had come to them about five years ago, as he was working through his past issues, Jack said.
"They were finally getting their lives back together," Jack recalled Tuesday. "They were doing exceptionally well."
More recently, he had been working as a handyman for the father of the children who were held hostage. The father, who is not being named because one of his children was the victim of a sex crime, declined to comment Tuesday, saying only "we're devastated."
The father's brother said they didn't have any clues that could have predicted this.
"We're in as much a shock as anyone else," the brother said.
Staff writers Sophia Chang and Jennifer Sinco Kelleher contributed to this story