However, legal experts said the section of law Judge Thokozile Masipa quoted when she announced the double-amputee Olympic athlete's sentence provides for a maximum of five years in prison and Pistorius could be released after 10 months in jail to serve the remainder of his sentence under house arrest.
Masipa also sentenced Pistorius to three years in prison for unlawfully firing a gun in a restaurant in a separate incident weeks before Steenkamp's 2013 shooting death. She ordered that sentence to be wholly suspended.
Masipa delivered her ruling after reviewing prosecution arguments for a tough sentence as well as the defence case for a more lenient punishment for Pistorius.
Pistorius killed Steenkamp on Valentine's Day last year, shooting her through a toilet door in his home. Pistorius testified that the shooting was an accident because he mistook his girlfriend for a nighttime intruder.
Masipa convicted him of culpable homicide, or negligent killing, but acquitted him of murder.
Pistorius stood as the judge announced his sentence, and then left the courtroom and walked down a flight of stairs that lead to holding cells. His sentence starts immediately.
Imray contributed from Stellenbosch, South Africa.
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