A deadbeat, rent-owing tenant shoved his Queens landlord down their building’s front stairs so hard on Sunday that the man later died — and the whole thing was caught on the home’s security camera, the victim’s grandson and police sources told the Post.

Landlord Edgar Moncayo, 71, was trying to collect rent around 3 p.m. at his 102nd Street building in Corona when 22-year-old tenant Alex Garces allegedly pushed him down the stairs, cops said.

His grandson, Nicolas Jativa, 20, told the Post that Moncayo was pronounced dead at 12:30 p.m. Monday after being on life support with head trauma at NYC Health + Hospitals/Elmhurst.

“My grandmother wasn’t home when this happened, she was on her way back home already when she got a call from a neighbor telling her what had happened,” the grieving grandson said. “As soon as she saw my grandfather she just dropped to her knees and started crying. I didn’t believe it until I saw the video for myself and it’s horrible.”

Police attributed Moncayo’s injuries to a landlord-tenant dispute and were looking for Garces and possibly a second person for questioning, according to officials.

The tenant initially told cops the fall was an accident that happened as he tried to carry his mattress out of the building and hit the front door, causing Moncayo to fall, police sources said.

But the landlord’s family reviewed video from the Ring video camera installed on their door and saw a horrifying series of events unfold.

In the video, the victim can be seen standing in front of the building on the phone with his wife trying to hold the door shut to keep Garces from leaving, the grandson said. The tenant was able to get the door open, however, and allegedly pushed the landlord down the steps, where his head hit the concrete, he said.

The landlord lives in the basement of the building with his wife, while the suspect — who failed to pay his last month’s rent — was living on the first floor, the sources said.

“It was all about rent, rent money that this guy didn’t want to pay,” the grandson said.

He said there had been problems since the tenant moved in last month. He had a woman and a child with him even though he said he’d be living alone, Jativa said.

“The kid was crying all night,” Jativa said. “My grandmother heard the kid crying from the basement and at 4 in the morning the kid is still crying so she goes upstairs and she tells him, ‘What is this? Are you guys leaving the kid unattended? He shouldn’t be crying this much.'”

Jativa said the family was broken up about the patriarch’s death.

“We were all hoping he would survive,” Jativa said of his grandfather. “Life takes its course.”