He grew up listening to his father’s anti-police rants. A lawsuit claims it drove him to murder.

Eric Frein is taken to prison after a hearing in Milford, Pa., in 2014. (Michael J. Mullen/AP/Scranton Times-Tribune)

Before drawing first blood in his guerrilla war, Eric Frein tapped his thoughts out in a letter.

It wasn’t exactly a suicide note, but he did acknowledge the long odds ahead. It wasn’t a last will and testament either, although Frein wrote that he wished to be buried in a simple wooden casket. And it also wasn’t a revolutionary screed soaked with anger or philosophical self-justification.

Instead, Frein — a jobless history geek with seven years of college credits but no degree — created a computer document on Dec. 29, 2013, at his northeastern Pennsylvania home.

He addressed the file to “Mom and Dad.”

“Our nation is far from what it was and what it should be,” the 31-year-old wrote. “I have seen so many depressing changes made in my time that I cannot imagine what it must be like for you. There is so much wrong and on so many levels only passing through the crucible of another revolution can get us back the liberties we once had. I do not pretend to know what that revolution will look like or even if it would be successful.”

He shaved his brown hair down to a mohawk and drove his parent’s Jeep to the Blooming Grove Station, a Pennsylvania State Police barracks surrounded by wooded land. There, Frein — a quiet guy whose main interest was staging military reenactments with friends — crouched in the brush.

At 11 p.m., when Cpl. Bryon Dickson II crossed his rifle scope, Frein opened fire with a .308 semiautomatic. Bullets pinned the 38-year-old married father of two to the ground. Another officer — Alex Douglass — was shot trying to pull his fellow officer to safety.

As Dickson died and Douglass suffered, Frein ran, eventually surrendering after a massive 48-day manhunt. At his trial, prosecutors portrayed the defendant as a domestic terrorist driven to violence by anti-government beliefs. Last April, a jury sentenced Frein to death.

But the question of blame in the 2014 attack remains unsettled, according to a new lawsuit.

Tiffany Dickson, the dead officer’s widow, is now suing Frein’s father and mother, Eugene and Deborah Frein of Canadensis, Pa. The wrongful death complaint, filed in Lackawanna County Common Pleas Court last week, alleges the parents not only missed warnings signs about their son’s troubles, but fueled the very anti-government beliefs driving Frein to violence.

The unique complaint turns the great anxiety of parenthood into a question of legality: Are a mother and father answerable for the crimes of the son?

“Cpl. Dickson’s death and the resulting loss to the Dickson family and the community is tragic,” the family’s attorney, Marion Munley, said in a statement to The Washington Post. “We will pursue justice for the Dickson family to the fullest extent of the law.”

Eugene and Deborah Frein did not return a phone message Tuesday evening. Their attorney also did not reply to a request for comment.

Frein’s relationship with his mother and father shadowed his criminal trial. Eugene Frein, in particular, emerged as a household’s dominating ego.

A career Army and National Guard officer, the older Frein retired after 28-years of military service with the rank of major. Eugene regaled friends and family with constant war stories about serving as a tank commander in Vietnam, according to the Morning Call. He also claimed he had fought as a sniper, trucking out regularly one particular anecdote about covering himself with excrement to hide from the Viet Cong.

But all those stories were fabrications, Eugene admitted at his son’s trial. He had never seen combat.

“It was a household full of false stories of a hero who was not a hero,” Frein’s attorney Michael Weinstein argued in court. “A child was raised amid that hero worship, and it was all a lie.”

The elder Frein also regularly sounded off about the current state of the government. One of the defendant’s friends — Warren Ahner — testified Frein’s father “ridiculed his son while complaining that Americans have become ‘sheep’ in a country where the Constitution is no longer respected,” the Morning Call reported.

When Eugene Frein testified in court, he spoke openly about his feelings for police. “The more they become militarized, the more they become like an army, and this country already has an Army,” the father said, according to PennLive.

Eugene, however, told the court he never encouraged his son to acts of violence.

“If [Eric] had a plan to shoot and kill anybody, I would have stopped him,” the father told jurors.

According to Tiffany Dickson’s recent lawsuit, that strange relationship between father and son is the skeleton key to understanding the younger Frein’s revolutionary furor.

“Eugene M. Frein, exercised significant influence over his son, Eric … with respect to Eugene M. Frein’s views on government, the police, and the use of firearms,” the lawsuit says. “Eugene regaled Eric with exaggerated stories about Eugene’s career in the military. Eric attempted to emulate his father but could not measure up.” The father also “related to Eric” his “theories about how he believed that the police wielded too much power.”

This amounted to, the complaint argues, a situation where the father “psychologically manipulated” the son “into developing a strong dislike for the police and acting upon that dislike by engaging in the aforementioned actions.”

The lawsuit also notes Frein was actively researching police stations to target, as well as stockpiling “numerous firearms, ammunition, and other supplies in his room that he subsequently utilized in his attack.” His parents, however, did not flag the behavior as troubling.

“As a result of the negligent, careless, reckless, and wanton acts and/or omissions” by the Freins, Dickson was killed.

The legal argument does have precedent in Pennsylvania. In 2000, Richard Baumhammers, an out-of-work white immigration attorney, killed five people in a racially-motivated rampage. Following a conviction, the families of the victims sued Baumhammers’s mother and father for failing to act on warning signs regarding their son’s mental health, the Associated Press reported. The case ended with a settlement.