Gisela Casella said Friday that she had assumed Jeffrey Johnson worked at a high-powered job because he always dressed neatly in a suit.
Police say Johnson fired three shots at Steven Ercolino outside the Manhattan landmark Friday morning. Johnson was fatally shot by police and nine other people were wounded. Their injuries were not life-threatening.
Some people have said Johnson threatened to kill Ercolino a year ago.
Casella lives in the Upper East Side building where Johnson lived. She said he was "so quiet but the nicest guy." She said he was always alone.
Casella said Johnson had two cats but one died last year. She said he looked stricken when he told her that his cat had died.
Investigators spent Friday night searching Johnson's apartment taking out some boxes of evidence.
Johnson also designed t-shirts.
"I can't believe it, he must have just snapped," said one neighbor.
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