The suspected madman behind a deadly stabbing spree in Manhattan Monday has a long criminal history — and had just walked free from Rikers Island a month before the terrifying attacks, The Post has learned.
Ramon Rivera, 51, identified by sources as the person of interest in the bloodbath, was released from jail Oct. 17 on a time-served sentence for a spate of recent burglary and assault convictions after spending most of this year behind bars, sources said.
The release perplexed Mayor Eric Adams, who said NYPD investigators were looking into how a career criminal with a history of mental illness could walk free, despite his recent convictions…