New York City Mayor Eric Adams pleaded with state leaders in Albany for help involuntarily relocating the mentally ill homeless from the city's streets and into care, characterizing a Monday stabbing spree as the latest casualty of New York's inaction.

"Everybody said I was inhumane, that we just want to institutionalize people," Adams said during a press briefing Tuesday. "Well, this is the result. This is the result of not taking actions and ignoring people who need help."

Adams said city officials will analyze how shortcomings in the criminal justice and mental health systems failed accused killer Ramon Rivera, who had been arrested eight times previously before allegedly killing three people on Monday.

"We have three New Yorkers who were murdered in our city by a person who was betrayed by the health care system," he said. 

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Rivera, 51, was caught when a good Samaritan cab driver alerted authorities, NYPD Chief of Detectives Joe Kenny said. 

He fatally stabbed a 36-year-old man standing outside a construction site on the city's West Side, then killed a second man who was fishing by stabbing him multiple times through his body, police said. Rivera allegedly attacked a woman a block away from the United Nations before he was taken into custody. That woman later died.

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Surveillance footage captured by a business on West 19th Street and obtained by the New York Post allegedly shows Rivera putting on gloves and preparing a knife before the string of attacks. Law enforcement sources told the New York Post that Rivera chose his victims because they were "alone" and "distracted."

Rivera spent most of this year behind bars and finished his most recent prison sentence for a spate of burglary and assault convictions on Oct. 17, the New York Post reported.

Rivera has a documented history of mental health concerns, and public records indicate he has had arrests or has been known to law enforcement in three other states, NBC News reported.

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Adams outlined steps the city has taken to take the mentally ill off the streets and subway systems, including efforts to shift toward small mental health "clubhouses" – day centers that connect them with community, art therapy and sometimes jobs.

However, Adams said that he needs help from the state's capitol. The Supportive Interventions Act, his bill to expand the city's authority to force the unwell off the streets and into psychiatric care, has not made it into law. 

"We’ve been back and forth to Albany to say let’s codify in law and give real clarity around the authority we have of dealing with people with severe mental health illness," he said in his Tuesday briefing. 

Rivera was arraigned on three counts of first-degree serial murder in a Manhattan courtroom hours after Adams' briefing. 

Fox News Digital's Max Bacall contributed to this report