'A Toxic Love Story' Ian Diaz's Stepfather Begged Judge for Mercy, Read Letter to Court

Ian Diaz's stepfather asked a federal judge to show compassion when it came time to sentence the former law enforcement officer featured in Netflix's "A Toxic Love Story" ... arguing prison would devastate Diaz's wife and young son.

According to documents obtained by TMZ, Diaz's stepfather -- Mark Doughty -- submitted a heartfelt letter to the court in June of 2023, describing Diaz as someone he's known since childhood ... saying he never knew him to be violent or "knowingly harmed anyone."

Doughty says the family proudly supported Diaz through the police academy -- later U.S. Marshals training -- and becoming a law enforcement officer had been Diaz's lifelong dream.

He says Diaz's graduation photo still hangs on their wall.

The letter says Diaz eventually found what he'd always wanted ... a family. Doughty tells the judge Diaz married his wife Amy, and the couple now shares a young son Tristan, who -- according to the filing -- is the center of Diaz's life.

Doughty says Diaz spends as much time with his family as possible -- taking them to Disneyland, Knott's Berry Farm and Medieval Times -- while also helping around the house so Amy can focus on her work as a full-time elementary school teacher ... adding, "He loves Tristan more than his own life."

According to the filing, Doughty fears a lengthy prison sentence would place enormous emotional and financial strain on the family ... describing how Amy would lose her husband's support, while Tristan would lose his father's daily presence during his childhood.

Addressing the conduct at the center of the criminal case, Doughty acknowledges Diaz "certainly made his mistakes," but argues the events were an isolated chapter in his life rather than a pattern of behavior ... and he writes that Diaz has since dedicated himself to being a husband and father, and deeply regrets everything that happened.

The letter closes with an emotional plea for leniency, asking the judge to "allow mercy to temper the sentence" ... arguing that both Diaz's wife and son would suffer tremendously if he is incarcerated for years.

Diaz's case was recently thrust back into the spotlight following the release of Netflix's "A Toxic Love Story," which focuses on Diaz and his then-wife Angela's plot to take down his ex Michelle Hadley.

The then-couple posted ads on Craigslist pretending to be Michelle looking for partners to help her with her "rape fantasy." They also falsely made it appear that Michelle was harassing Angela.