PRETORIA - A South African judge on Tuesday sentenced Olympic and Paralympic track star Oscar Pistorius to five years in prison for the negligent killing of his girlfriend Reeva Steenkamp on Valentine's Day last year.At the culmination of one of the most watched murder trials in recent history, the 27-year-old disabled sprinter was led away by police officers to holding cells beneath the courtroom in Pretoria.Pistorius wiped his eyes as Judge Thokozile Masipa handed down the prison sentence for culpable homicide.Masipa - only the second black woman to rise to South Africa's bench - said the sentence had to be "fair and just to society and to the accused."There was no immediate reaction from members of the athlete's family, or from relatives of Steenkamp, a 29-year-old law graduate and model."Justice was served," said Dup De Bruyn, the lawyer for the Steenkamp family. He told reporters the judge had given "the right sentence."Pistorius's defense lawyer Barry Roux said he expected the jailed athlete to serve only 10 months of the five-year sentence behind bars, and the remainder under house arrest.However, South Africa's state prosecuting authority disputed this opinion, saying Pistorius was likely to serve at least a third of his sentence in prison - effectively 20 months.On a separate firearms charge for which Pistorius was also found guilty, Masipa gave him a three-year suspended sentence.Steenkamp was killed almost instantly when Pistorius fired four shots through a bathroom door at his luxury Pretoria home on Valentine's Day last year, having mistaken her for an intruder.The athlete, known as 'Blade Runner' because of his carbon-fiber prosthetics, became one of the biggest names in world athletics at the London 2012 Olympics when he reached the semifinals of the 400m against able-bodied athletes.