A 40-year-old man was held 291 days past his prison release date because state officials couldn’t find housing to treat his bipolar and depressive disorders, says a new lawsuit — and he was one of an unknown number of mentally ill New York prisoners in the same situation.

The man, who sued in Manhattan Federal Court under the initials A.D., says he should have been released on parole Nov. 24, 2017 for criminal sale of a controlled substance. Instead, he walked out of Fishkill Correctional Facility in Sept. 10, 2018.

“It definitely came as a surprise and at such a bad time. I had family awaiting my arrival. And a son that was waiting for me,” A.D. told the Daily News in an interview. “I was at a loss for words. I did not know it could be done. I had served my time. It was a real shocker to me.”

A.D. recalled packing up his belongings in prison and being processed for release, eagerly awaiting the chance to get his life on track.

But one day before his release date, prison staff asked him to sign a paper saying he would remain in custody, A.D. recalled. He was supposed to be sent to a residential treatment facility, but the state couldn’t find “appropriate community-based mental health housing,” the suit states.

“I’m just lost in the system,” A.D. recalled thinking.

A.D. said officials gave several reasons why he was still behind bars. He said he was told his dose of the antipsychotic Seroquel was too high to be released. Officials rejected A.D.’s proposals he move into friends’ homes, he said.

“They were saying I wasn’t stable to go into a shelter, which was not valid, because I had already been in a shelter. I was homeless for two years before I got arrested…I was on medication — the same meds I was on,” he said.

He’d stewed behind bars a whopping 210 days past the maximum sentence allowed for selling cocaine, the suit states.

A.D. said his mental illness was tied to drug addiction. He’s now sober and works for a medical billing company.

A.D.’s attorney, William Igbokwe, estimated there are dozens — or hundreds — of other inmates facing a similar predicament. A.W. recalled a few inmates telling him they also were being held past their release date, but he did not know the details of their cases.

Legal Aid Society lawyers in 2019 filed a class-action lawsuit in Manhattan Federal Court against the state on behalf of prisoners like A.D. Filings in the case say the Legal Aid lawyers and the state are in settlement talks.

In the suit, Legal Aid accuses the state of holding prisoners “past their release dates—including the end of their prison sentences, approved conditional release dates, and open dates for parole” because New York lacks adequate “community-based mental health housing programs” to help them.

By holding mentally ill prisoners past their release dates, Legal Aid says, the state is “undermining the most basic principle undergirding the criminal justice system: that a criminal sentence, once imposed by a judge, means what it says.”

A spokesman for the state prison system did not respond to a question about how many inmates are being held past their release dates. The agency does not comment on pending litigation.

A spokesman for the State Office of Mental Health said it would respond to A.D.’s allegations in a public court filing.

Officials eventually released A.D. into a sober living facility in his hometown of Freeport, L.I. The adjustment hasn’t been easy.

“The first six months I came back I didn’t wanna work, or be social, or even leave the house because of the fear of catching another crime. I don’t want to go back in (to prison) out of the fear of never coming back. Because that is how it felt: like I was just going to get lost,” A.D. said. “I’m still trying to integrate socially. It’s just really a permanent scar from this.”