This photo provided by Linda Clary shows a selfie she took with her son John Umberger, November 2015, in Washington. Multiple people, including Umberger, have been fatally poisoned with narcotics in what investigators say were schemes by criminal crews to incapacitate and rob people at New York City bars and nightclubs. (Linda Clary via AP)

NEW YORK (AP) — Multiple people have been fatally poisoned with narcotics in what investigators say were schemes by criminal crews to incapacitate and rob people at New York City bars and nightclubs.

The killings — at least five, according to police — stretch back months and appear to be the work of different crews, operating independently from each other but using similar tactics, police and prosecutors said Thursday.

Men surreptitiously slip revelers dangerous levels of drugs to knock them out, then take their wallets and phones, sometimes using their digital banking info to drain their accounts.

In March, Nurbu Sherpa, a 29-year-old chef, was found dead on the sidewalk after leaving a bar where he had been celebrating St. Patrick’s Day.

In April, Julio Ramirez, a 25-year-old social worker, died in a taxi after leaving a Manhattan bar with a group of men. Later, relatives discovered some of his savings had been stolen.

In May, John Umberger, a 33-year-old political consultant visiting from Washington D.C., was found dead of an apparent drug overdose in the townhouse where he was staying. Surveillance video showed him leaving a popular club being propped up by a group of men. Money was also taken from his bank account.

Other men have come forward with stories about being drugged by strangers and waking up to find money gone.

Many of the crimes remain unsolved, but the Manhattan district attorney on Thursday announced that one suspect, Kenwood Allen, of the Bronx, had been charged with murder in Sherpa’s death and in the killing of Ardijan Berisha, 26.

Berisha, of South Salem, New York, and a friend passed out on the sidewalk in July after drinking at a bar on Manhattan’s Lower East Side.

Allen drugged both of his victims with fentanyl, prosecutors said, then robbed them. He is accused in three other instances where victims survived.

Allen’s sister told the Daily News her brother is innocent.

“My brother is not a murderer,” said Lauren Allen, 39. “My brother has always taken care of his family, his mother and his sisters. He’s not in no gang. He’s not in some crew going around drugging and robbing people. That’s just not true, that’s ridiculous.”

No one has been charged in the other killings, which are still under investigation.

“Nobody should have to worry that a night out at a Manhattan bar with friends could end in tragedy,” Manhattan District Attorney Alvin Bragg said.

At a news conference Thursday, New York Police Department Lt. Det. Dave Leonardi said some of the victims were given a mix of drugs including lidocaine, fentanyl and cocaine — with lidocaine being the substance that really incapacitated them.

The deaths of Ramirez and Umberger prompted concern that gay men were being targeted. Both died after leaving Manhattan LGBTQ bars. Some victims and their relatives have complained that the crimes weren’t treated with more urgency by police.

Umberger’s mother, Linda Clary of Dawsonville, Georgia, said that after hearing about Ramirez’s death and stories from others, she felt frustrated by authorities’ response.

“There were enough cases reported that NYPD should have sounded the warning bells to say this is going on, people need to be careful, but they didn’t,” she said.

NYPD Chief of Detectives James Essig said robberies have occurred beyond the gay community.

“We don’t particularly think they’re targeting gay members,” he said. “This is based solely on monetary gain.”

Still, unease about possible targeting remains, especially in an environment when an anti-LGBTQ atmosphere has been felt around the country, said Beverly Tillary, executive director of the New York City Anti-Violence Project, an organization that advocates for LGBTQ communities.

“There’s some sense of being on edge,” she said, “and not knowing what might happen next in terms of attacks on our community.”