PRETORIA, South Africa — Oscar Pistorius, the double-amputee Olympian described by a judge as a “fallen hero,” was sentenced today to six years in a South African prison for the murder of girlfriend Reeva Steenkamp, in a ruling viewed by some as too lenient.

However, Judge Thokozile Masipa appeared to anticipate criticism of a jail term that fell far short of the normally mandated 15 years for murder under South African law, declaring: “Our courts are courts of law, not courts of public opinion.”

Pistorius, who shot Steenkamp through the door of a toilet cubicle in his home in 2013, was asked to stand and face Masipa as she announced his sentence in a wood-paneled courtroom in the South African capital, Pretoria. He was calm after the ruling, embracing his aunt and tearful sister before being led down a courtroom staircase to a holding cell ahead of being taken to prison.

Later, a convoy of police cars with lights flashing and sirens wailing left a side entrance of the courthouse. In the convoy was a van with tinted windows, possibly carrying Pistorius.