Richard Keller, 54, was at his mother's 11th-floor luxury co-op on 56th St in Manhattan when he stabbed his elderly mother five times.
Neighbors in the building heard yelling and screaming.
Mindy Pollock, a neighbor that lived on the same floor, said she heard the argument but could not make out what was being said. When police entered the scene they found prescription bottles with the son's name on them.
And it was soon clear that the son had some mental problems. Eliot Dimant, 30, said this kind of thing is unheard of living here. Richard was arrested like nothing was going on and was cooperative. Tenants of this 40-story building where shocked.