The 24-year-old man arrested in connection with the killing of Francesco Cali, a reputed boss of the Gambino crime family who was gunned down in a brazen hit last March, believed he was under the personal protection of President Trump in a battle against the "Deep State," according new to court papers.

Anthony Comello was arrested shortly after Cali's death on charges of murder, assault and criminal possession of a weapon. For at least one of his court appearances, he had pro-Trump slogans, including "MAGA Forever," scrawled on his hand.

Also on his palm: a symbol for QAnon, a conspiracy theory about the president widely circulated on 4Chan and other far-right message boards. 

In the months prior to Cali's death, Comello became absorbed with QAnon, according to the papers, which are dated last Friday.

"As part of his delusion, the defendant believed that he had been given secret knowledge about the Deep State, and that Q was communicating directly with him so that the defendant could play a grand role in the conflict to save the American way of life. Because of his self-perceived status in QAnon, Mr. Comello became certain that he was enjoying the protection of President Trump himself, and that he had the president's full support," attorney Robert Gottlieb wrote. 

Gottlieb went on to say that Comello was actually attempting to effect a citizen's arrest of Cali, given Comello's belief that Cali was also linked to the "Deep State." 

"The defendant had brought handcuffs with him, and planned to restrain Mr. Cali and bring him to the appropriate authorities to answer for the criminal actions which Mr. Comello believed he had taken part in," Gottlieb wrote.

When Cali made what the lawyer described as a "furtive action with his hand," Comello reached for his gun and shot Cali in what attorneys claimed was self-defense. Gottlieb made the argument in support of a motion to throw out the second-degree murder charge, saying Comello had no intent to kill Cali, only arrest him. 

In the days after the killing, law enforcement sources said the Cali killing appeared to be personal, not about a beef with the mafia. They've also described Comello's behavior as erratic, and Gottlieb echoed as much outside court earlier this year. 

"Family and friends recognized and picked up significant changes in him over the past few months," Gottlieb said outside court in March. "Something clearly went wrong." 

Cali, known as "Franky Boy," was shot to death in front of his home on Hilltop Terrace not long after dinnertime March 13. Authorities said 12 shots were fired, with at least six striking Cali, who tried to use his car as a shield to protect himself during the shooting. A bloody handprint was evident on the vehicle.

Federal prosecutors in Brooklyn had referred to Cali in court filings in recent years as the underboss of the Gambino organization, related through marriage to the Inzerillo clan in the Sicilian Mafia.

Multiple press accounts since 2015 said Cali had ascended to the top spot in the gang, although he never faced a criminal charge saying so.

His only mob-related criminal conviction came a decade ago, when Cali pleaded guilty in an extortion conspiracy involving a failed attempt to build a NASCAR track on Staten Island. He was sentenced to 16 months in federal prison and was released in 2009.