NEW YORK -- The man accused ofin Queens has been charged with murder.
Friday, police were outside the suspect's apartment waiting for a search warrant to go through his home. Sources said they're looking for the murder weapon, CBS2's Alice Gainer reported.
Just feet away from the suspect's home, a memorial has been growing where Russo was killed in what was described as a vicious, unprovoked attack.
Purple and black bunting hang at EMS Station 49,
"She was such a great person, a heart of gold. She was here for the whole station. She made sure that we were all OK," said Madelyn Higueros, a paramedic.
Russo, 61, was on duty Thursday afternoon when she left to get food after 2 p.m. About a block away on 41st Street and 20th Avenue, Russo was caught off-guard by, according to police and witnesses, 34-year-old Peter Zisopoulos.
"I knew something was wrong with him, just the way he was weirdly pacing," said Jimmy Orsaris.
Orsaris was on his scooter when he said he saw Zisopoulos suddenly charge at Russo.
"He just went just a hundred miles an hour. Grabbed this poor lady, just dropped her to the floor. And then, at first I thought he was punching her," Orsaris said. "I'm screaming, cursing, 'Stop, stop, stop!' and he screams out, 'Yo, F you!'"
"I can't explain the face he had. He just, like, he wasn't here," said Orsaris.
Orsaris got off his scooter and saw the knife.
"I realized he was stabbing her, knife in his hands and the look of nothing in his face. I'm screaming at him, he gets up and just charges after me," said Orsaris. "Obviously I take off. I mean, I have a knife on me too, but what, am I going to have a knife battle with this guy? This guy ... he wasn't there."
According to police sources, Russo was stabbed more than 20 times in the neck, chest and torso. An auto shop worker chased Zisopoulos, who ran into his apartment and barricaded himself inside until hostage negotiators got him out.
Police sources said Zisopoulos had one prior interaction with the NYPD. They were called to his home because he was acting erratically and making physical threats in 2018. He was classified as an emotionally disturbed person and taken to the hospital.
We're told Zisopoulos has a history of schizophrenia. While in custody for the attack on Russo, he was pacing back and forth in the cell and talking gibberish.
Orsaris returned to the scene moments after the stabbing. But the attack happened so fast, he doesn't believe there was anything anyone could do. Meantime, he is deeply haunted by what he witnessed.
"I keep playing it in my head over and over and over again," he said.
Zisopoulos is charged with murder and criminal possession of a weapon. Law enforcement sources said he was taken to the hospital for evaluation.
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