The man accused of shooting three people – killing his building’s superintendent – in a rage-fueled rampage over a shared backyard died in custody on Rikers Island over the weekend, officials said. 

Jimmy Avila, 44 – arrested in connection to the Wednesday murder of 37-year-old Ryan Hines inside a Mount Eden apartment building – was found lifeless around 4:30 p.m. Saturday inside the jail complex’s West Facility, according to the city’s Department of Correction. 

Jail staff came to Avila’s aid, soon joined by medical staff and EMS, but he could not be revived and was pronounced dead. 

“Our hearts are heavy with the loss of an individual in our care,” DOC Commissioner Lynelle Maginley-Liddie said in a statement. “We mourn his passing and extend our sympathies to his loved ones. We will thoroughly investigate the circumstances of this tragic event.”

The circumstances of Avila’s death are “pending further study” following an autopsy on Sunday, according to the city medical examiner’s office. 

The Legal Aid Society, which represented Avila in the murder case, said their client suffered from “serious mental health issues” and that “given his condition, this should have been immediately flagged at intake, and he should have been under DOC’s close watch.”

“Moreover, the fact that defense counsel found out about his death from a press release instead of outreach from the Department is completely unacceptable,” the non-profit organization said in a statement. “With each of these deaths, the City responds with the same boilerplate language, but conditions don’t improve, the people we represent continue to suffer, and these tragic deaths continue to mount.”

Avila’s death came a day after he was ordered held without bail in Bronx Criminal Court in connection to the murder, online records show.

He was accused of opening fire around 8:30 a.m. Wednesday inside the building on College Avenue near East 170th Street in Mount Eden — striking Hines in the chest, hitting a 59-year-old in the buttocks and shooting a 62-year-old in the arm.

Hines later died of his injuries, but the other two were hospitalized in stable condition.

Law enforcement sources and neighbors said Avila lost his temper during an ongoing dispute with neighbors over their shared backyard.

Avila barricaded himself inside an apartment — and called News 12 to confess — before he was eventually arrested after a stand-off with police.

“I didn’t mean to do this, but I had to do it because these people were threatening my life, everything and stuff like that,” he told the station. 

He had reached out to the network multiple times in the past over feuds with his building’s management and super, the outlet reported. 

Avila reportedly believed the backyard was his alone because he lived on the first floor, the Daily News reported.

The deadly shooting came in the middle of a bloody week across the Bronx that sparked Mayor Eric Adams to deploy 1,000 cops to violent hotspots in the northernmost borough over the weekend to stop the bloodshed. 

The DOC said it has notified the federal monitor, the Board of Correction, the state Attorney General’s Office, the city’s Department of Investigation, the state Commission of Correction, the ME’s office and district attorneys of Avila’s death. 

The latest in-custody death came exactly a week after Ardit Billa, 29, who was being held for burglary, was found “unresponsive” in his lockup by officers conducting routine tours at Rikers Island’s George R. Vierno Center, according to the DOC. 

He too was pronounced dead despite life-saving efforts.