A New York City hospital is being sued after video showed a man with a head injury sitting in an emergency room so long he slipped into a coma before he was noticed by workers there.

The family of Angel Rivera says that the 53-year-old spent two years in that coma and died in 2016 without ever waking up after going to the ER at Lincoln Hospital in the Bronx in 2014. Video from the hospital shows Rivera sitting unattended for more than 9 hours before someone noticed him unconscious and bleeding from the nose.

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Rivera’s son, Angel Rivera Jr. told News 4 that after his father died, a doctor told him that had he been noticed sooner, he’d still be alive today.

"You expect to have care in a timely manner -- not to be lost in the system for 9 hours," he said. "I'm enraged, but I'm keeping my composure because I have to be strong for my family."

Rivera went to the hospital after getting punched in the head during a fight with a friend, according to the family.

He was initially tended to as hospital workers saw him in a triage room. But once he was told to stay and be monitored in a secondary waiting area, he slipped between the cracks.

At one point hours later, hospital workers called his name, and when he didn’t respond, the family said workers assumed he’d walked out.

But he was still there -- nearly 10 hours of video showed he had never left.

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"They lost him in plain sight," said Mark Brodner, the family's attorney. "He was within feet of hospital personnel who for a period of 9 hours didn't remember that he was even there."

Hospital workers eventually tended to Rivera a second time, and video shows him being loaded into a gurney. But his family said he never again regained consciousness.

Lincoln Hospital said in a statement that patient confidentiality laws preclude them from commenting on the case.

But the hospital added, "We nevertheless extend our heartfelt sympathies to the family members of Mr. Rivera."

Angel Rivera Jr., meanwhile, said the hospital "took a life" and that they should change their waiting-room policies.

"Not knowing he was there they took a life and that's difficult for me to process," he said.

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