Rigoberto Lopez was ordered held without bail at his arraignment Monday morning in connection with four violent subway attacks.
Prosecutors say the 21-year-old man admitted to all four attacks and has a history of drug and assault arrests.
Lopez was taken into custody late Saturday and charged with murder and attempted murder in connection with the stabbing deaths of two homeless people on an A train and a knife attack on two others at the 181st station in Washington Heights, where he was apprehended.
Detectives were able to track Lopez down using video surveillance.
RELATED: Subway stabbing suspect had knife on him when he was arrested
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He was found with bloody clothes and a knife which, according to investigators, Lopez himself identified as the murder weapon.
The NYPD has now assigned an extra 500 additional officers to the city's subway system after a string of attacks in recent months has led to calls for increased police presence.
Mayor Bill de Blasio rode the downtown 5 train Monday night to assure riders the subways are safe. Of course, he was surrounded by police.
"I want people to know, we're going to do whatever the hell it takes to keep subways safe," de Blasio said.
However, transit officials say 1,000 more cops are needed.
According to the MTA, ridership is down 70 percent on subways and 50 percent on buses.
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But felony assaults are up by more than 25 percent, due to a surge in homeless and mentally ill people on trains.
Transit officials have long said the subways must not be a dumping ground for the city's vulnerable and violent population.
2 fatally stabbed on separate subway trains; NYPD to increase patrol
Meanwhile Police Commissioner Dermot Shea and Mayor Bill de Blasio have been touting statistics show show crime overall is actually down.
Governor Andrew Cuomo is expected to address this issue in a briefing Monday afternoon.
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