Firefighters working to put out the flames at the building.

The shattered father of a young college graduate who perished in the 2015 fatal East Village building explosion took the stand Monday at the start of the trial of a landlord and two workers accused of causing the blast.

Dad Nixon Figueroa recalled how his wife waited nearly three agonizing days after the March 26, 2015, blast to learn that the body of their 23-year-old son was recovered from the rubble.

“That’s the day I died,” said the 56-year-old, choking up. “I have a picture of my son’s face in the moment when he’s flying through the air and the anguish that he had and the pain when he knew he wasn’t coming back…it broke my heart.”

Figueroa had been wrapping up a lunch-date at the restaurant Sushi Park, which occupied the ground floor of 121 Second Avenue, when a massive explosion and fire tore through the building. The eatery’s busboy Moises Locon, 27, also perished in the blaze and 13 others were injured.

The manslaughter trial of landlord Maria Hrynenko, 59, contractor Dilber Kukic, 44, and unlicensed plumber Athanasios “Jerry” Ioannidis, 63, started Monday morning.

The stricken father, who was the prosecution’s first witness, said that before his son died, “I’m sure he called out for me.” As his eyes welled with tears, he said, “I did everything for this boy.”

The younger Figueroa had just graduated from Buffalo State College and was working at a bowling alley at Chelsea Piers. The father recalled seeing his son at the morgue. “I wanted to just hug my son. To see my beautiful son dead there — for what? For what?” he said, wiping away a tear, as Hrynenko, sitting at the defense table, dabbed at her eyes with a tissue.

Zacharia Locon, 25, described through an interpreter the frantic search for his brother, Moises Locon, whose body was also discovered three days after the explosion under the debris.

“They told us we couldn’t see him because we wouldn’t be able to recognize him,” the brother recalled, weeping. Prosecutors say that Locon had burns covering 100 percent of his body, and he had to be identified through DNA.

Assistant DA Randolph Clarke Jr. argued in opening statements that the defendants were motivated by greed when they illegally tapped into the gas line of the neighboring building, 119 Second Avenue, also owned by Hrynenko.

“[The defendants] took a chance, they rolled the dice and the cost was paid by Mr Figueroa and Mr. Locon and 13 others,” Clarke told the jury in Manhattan Supreme Court.

Hrynenko hired Kukic to renovate the four apartments above Sushi Park and wanted to rent them out before Con Ed signed off on new gas meters.

The defendants illegally tapped into Sushi Park’s gas line, which Con Ed already determined wasn’t able to handle the load of the additional apartments.

Con Ed returned to the building for a meter reading in August 2014, detected a gas odor and discovered the illegal apparatus and a leak.

They shut off the gas and Hrynenko had the makeshift gas supply system removed before service was restored a week later.

Clarke said that’s when the defendants hatched a plan to divert gas from 119 Second Ave. to supply the apartment at 121 Second Avenue, using a series of pipes and valves. The illegal hookup was hidden behind a locked basement door.

On March 26, 2015, Kukic shut off the gas before a scheduled Con Ed inspection related to the new meters at 121 Second Ave. Con Ed reps conducted tests opening several valves and didn’t close them.

After they left, Kukic and Hrynenko’s now-deceased son turned the illegal gas hook up back on not realizing the valves were still open.

It took just 23 minutes of gas streaming into the basement and ground floor to cause the explosion.

Hrynenko’s defense lawyer Michael Burke said one of the injured was her own son, Michael Hrynenko Jr., who died while awaiting trial, and she would have never intentionally put him at risk.

He said that the fire marshal determined that the explosion and fire occurred in the first floor kitchen of the sushi restaurant, where Con Ed had been dispatched repeatedly over reports of a gas leak, and not the basement.

Kukic’s defense lawyer Marc Agnifilo also argued that the prosecution didn’t have enough evidence to support their theory of the explosion and that the gas leak may have come from a faulty line that supplied the restaurant’s kitchen.

He said that on the day of the blast people reported a gas odor in the restaurant, not the basement. He added that, “They heard a loud hissing sound coming from the kitchen of the sushi bar.”

Ioannidis’ attorney Roger Blank said, “This is an awful, terrible accident but it is not a crime.”

The defendants face manslaughter, assault, criminally negligent homicide and other charges.

The elder Figueroa told reporters as he left the courthouse that he wanted to see the defendants in jail. “If they did the crime, they should pay the price,” he said.