He fell asleep at his sentencing, which saw him being slapped with 50 years to life in prison.
Daniel St. Hubert was found guilty of killing a six-year-old boy and severely wounding a seven-year-old boy in 2014.
A photo shared by NY Daily News showed St. Hubert, a homeless man, falling asleep with his mouth open while being seated next to his defense attorney.
The 31-year-old later protested the decision, launching into a diatribe about his innocence.
"I've been saying from the beginning I'm innocent. Can you look me in the face, your honor, and see I'm a good guy?" he told Judge Vincent Del Giudice.
He said he has been a good person all his life and that he had been chasing a career in Hollywood.
But the judge dismissed St. Hubert's pleading, saying that he committed an "unspeakable horror" and that he hopes he will never regain his freedom.
St. Hubert had been charged with second-degree murder and second-degree attempted murder charges following the gruesome 2014 attack inside an elevator
P.J. Avitto was pronounced dead in the hospital while Mikayla Capers, now 11 years old, survived the attack.
The children were on their way to P.J.'s sixth-floor apartment after playing tag when St. Hubert followed them into the elevator of 845 Schenk Ave. He attacked the children with a nine-inch steak knife.
P.J. died at Brookdale Hospital. Mikayla, whose wounded lung collapsed, spent nine days in the hospital.
Mikayla appeared in the court during the sentencing. She delivered a speech before the judge.
"Sometimes I try not to remember...but every day I must look at my 16 stab wounds," she said.
"I will always remember [P.J.'s] smiling face and the fun we had. I ask the bad man Daniel St. Hubert to be sent to jail for the rest of his life," she said.