The Paralympic champion was cleared of premeditated murder and second degree murder after shooting dead his girlfriend Reeva Steenkamp on Valentine's Day last year.
The judge told the High Court in Pretoria today that there was not enough evidence to prove that Pistorius intended to kill the South African model when he fired four gunshots through a toilet door at his home in the early hours of February 14, 2013.
However, she raised the possibility of culpable homicide (manslaughter) by telling the court: "I am convinced he acted too hastily and used excessive force. It's clear that his conduct was negligent."
Pistorius, who denied murder by claiming that he mistook Steenkamp for an intruder, could face a maximum prison sentence of 15 years.