Ex-convict with 15 previous arrests arrested for random stabbing of teenager in New York where he smiled at blood-soaked victim

An ex-convict with 15 previous arrests was arrested for randomly stabbing a teenager in the neck near City Hall and then giving the victim a menacing smile, police said Thursday.

Grinning maniac Marvin Dupree, 41, allegedly walked up behind Brooklyn College student Alan Ryvkin and stabbed him in the neck around 11:30 a.m. as the 19-year-old waited outside a building on Center Street, according to authorities to contest a car citation.

Police caught up with the alleged grinning slasher in Harlem hours after the attack and charged him with assault, authorities said.

Ryvkin said he was talking to a woman just outside the building at 1 Center St. when the stranger quietly walked up behind him and stabbed him.

“As he walked away, the guy looked at me and smiled with the knife in his hand,” Ryvkin told The Post exclusively over the phone on Wednesday.

“I didn’t know who it was. I don’t know what it is. I’ve been stabbed and I’m sitting on the floor and starting to bleed to death.”

Sam Townsell, 24, a bartender at the outdoor Jury Duty Bar, watched as a bloodied, apparently shocked Ryvkin was loaded into an ambulance.

She said she was shocked as the late morning violence unfolded just steps from NYPD headquarters.

“It’s scary — there’s a police station right there,” Townsell said.

“You wouldn’t think that in an area like this, where there are police officers everywhere, that there would be such violence. There’s nowhere here where you wouldn’t see a police officer, so it’s kind of scary.”

Paramedics rushed Ryvkin to Bellevue Hospital, where doctors treated him for a stab wound between his lower neck and upper back.

“It’s terrible,” said the lifelong New Yorker. “There is a feeling that New York is not the right place. It’s very unsafe.”

Meanwhile, Dupree was also taken to Bellevue after his arrest for unknown reasons, cops said.

Dupree’s criminal record includes charges of assault, aggravated harassment, criminal possession of a controlled substance, menacing and resisting arrest, cops said.

He was last arrested in July for threatening behavior in Harlem, but the case has since been closed, police said.

His last attack occurred in June 2012, also in Harlem, but that case has also been closed, according to authorities.

He has a prior conviction for criminal sale of a controlled substance and served just over four years in state prison before being paroled in November 2019, records show.

He previously served about six years in prison for drug trafficking before being released on parole in October 2013. Records show he served less than a year in prison for drug possession until he was paroled in July 2006.