MANHATTAN (PIX11) — An attacker who stabbed three homeless men in separate incidents, killing one of them, took one of the victim’s bike for a spin before the deadly assault, police said Tuesday.

He also stared at one of the men before the stabbing. The series of attacks started on July 5, with the most recent stabbing happening on Monday. No arrests have been made and police believe the attacker is armed and dangerous.

During the first incident, the 34-year-old victim was sleeping on a bench inside Hudson River Park, police said. The attacker took the victim’s bike for a ride before returning and stabbing the man. The victim woke up and stumbled across the street for help. A passerby called 911, but the victim succumbed to his injuries at a hospital.

On Friday, the attacker watched the victim for a half-hour as he slept on a bench on Madison Avenue near East 49th Street, police said. He put on a mask, walked over, stabbed the victim and then left.

The suspect struck again on Monday around 3:30 a.m. at the Stanley Isaac Playground along the FDR Drive, police said. The victim was asleep on the basketball court and woke up when he was attacked. He chased the stabber, but didn’t make it far because of his wounds, police said.

“We are asking the public’s help and we need the public’s help before he strikes again,” NYPD Chief of Detectives James Essig said.

As they search for the attacker, police are showing the man’s photo to homeless individuals. Officers are also urging homeless New Yorkers to head to shelters.

All of the victims were stabbed in the stomach, according to investigators. No words were exchanged between the suspect and victims before the attacks.

The attacker wore an “Innocence Project” sweatshirt during two of the attacks, but police do not believe he has any association with the organization. A spokesperson for the organization explained that thousands of the sweatshirts have been distributed over time.

The attacker also wore bright, neon sneakers. One witness said the man had a large kitchen knife.

Submit tips to police by calling Crime Stoppers at 1-800-577-TIPS (8477), visiting, downloading the NYPD Crime Stoppers mobile app, or texting 274637 (CRIMES) then entering TIP577. Spanish-speaking callers are asked to dial 1-888-57-PISTA (74782).