Justyna Rzewinski left her job as a clinical supervisor for mental health on Rikers Island just three weeks ago.

Her job: to work with some of the island’s most seriously mentally ill detainees.

“I just couldn’t be there anymore, just seeing these individuals being locked in a lot of the time,” Rzewinski told NY1. “I couldn’t even sit in my office cause they were screaming and banging and I would hear them and it was really difficult to pretend that it’s not happening and do work.”

Rzewinski sat down with NY1 in her first television interview to share her story, days after uncovering a practice she says is standard operating procedure in the city’s mental health units on Rikers —locking seriously mentally ill detainees in their cells for days, weeks or even months at a time.

“It really depended, but I did have patients who were locked in for weeks, over a month, and a lot of patients would rotate from one mental health unit to another. So they were locked in one unit, they’d be locked in another unit. So, it could be a few months,” Rzewinski said after NY1 asked how long people were locked in for.

“When they’re locked in, they’re not getting their medications because their medications come on the unit or in the bubble so they’re not able to come out of their cell to line up to get their medication, and this is not just psychiatric medication, it’s also medical,” Rzewinski said.

She says that’s when detainees would decompensate.

“They’ll smear feces. Talk to themselves. Sometimes not move. And sometimes flood the cells,” Rzewinski said. “A lot of times they bang. They scream because they want to be released.”

The process, she says, is called deadlocking.

“There is a control panel where they open up and close the cells and the cells are numbered. They put a white piece of paper on it and that means the person is locked in,” she said of the practice.

Rzewinski says it happens at the city’s specialized mental health units on Rikers — where she claims correction officers will decide if a detainee gets locked in their cells for extended periods of time.

That decision could be made, she said, if a detainee looked at an officer the wrong way.

City jail rules say lock-ins should not occur for longer than two hours, and no detainee with serious mental illness should ever be held in solitary confinement.

This week, correction officials said they will investigate her claims, but still insisted the jail complex does not have solitary confinement. The Board of Correction, the jails oversight body, is also investigating.

At a meeting this week, where Rzewinski testified, sharing her story, jail health officials did not deny the practice happened.

“We’re working on systems to help essentially identify how this is happening,” Dr. Bipin Subedi of Correctional Health Services said.

The detainee population with mental illness has been climbing over the years. More than half of detainees on Rikers Island get some sort of mental health services, according to the jail’s health care provider. As of August, 20% have a serious mental illness.

Now the question is, can the city care for them?

“So I don’t think these individuals should be on Rikers because obviously they can’t handle these patients,” Rzewinski said.