PRETORIA, South Africa - Oscar Pistorius was sentenced to five years in prison on Tuesday for killing his girlfriend Reeva Steenkamp with four shots from a handgun on Valentine's Day 2013.

Pistorius remained emotionless as the sentence was read, but bowed his head slightly as the legal teams concluded proceedings and cried quietly.

His lawyer, Barry Roux, said after the sentencing that Pistorius was expected to actually serve 10 months behind bars and the remainder of his sentence under house arrest. CBS News' Debora Patta says the 10-month mark is the earliest Pistorius can apply for a transfer from prison to house arrest.

The former Paralympic double-amputee track star known as "Blade Runner" -- who shot to international fame when he was granted permission to run in the 2012 Olympics alongside able-bodies athletes -- has maintained since the day of the shooting that he believed an intruder entered his home and was hiding behind the locked bathroom cubicle door.

Prosecutors argued that he knew it was Steenkamp behind the door in his luxury house and that he shot her in a fit of rage after an argument.

Both the prosecution and Pistorius' legal team have the option of appealing Judge Thokozile Masipa's sentence.

She sentenced him to five years for killing Steenkamp, and an additional three years for the unlawful discharge of a firearm in a restaurant in a separate incident. She suspended the three-year sentence for the discharge of a firearm for a period of five years.

Patta reports that as he was led out of the courtroom on his way to a high security prison, Pistorious reached out for support for his family. Almost immediately after the sentencing, his uncle Arnold told reporters in a brief statement that the family "accept the judgement" passed by Masipa.

Steenkamp's family looked relieved in court, reports Patta, and outside the courtroom her mother June was seen smiling for first time in months before she was engulfed in reporters and cameras jostling to ask her questions. She said she believed justice had been served.

In the final phase of the trial Pistorius' legal team called one witness who argued that the runner's disability would make a prison sentence unduly hard for him to bear. Masipa chastised the witness before announcing her punishment on Tuesday, saying she believed the South African prison system was capable of handling an inmate with physical disabilities.

"I have no reason to believe the accused would present the department of corrections with an insurmountable challenge," Masipa told the court.

Masipa said the key mitigating factors she considered in her sentencing were that Pistorius was a "first offender and seems remorseful." She also took into account his actions immediately after the shooting, "which indicated that he wanted the deceased to live."

The judge said she attempted to strike a balance in determining her sentence, which she must "neither be too severe nor too light."

Pistorius was surrounded by police officers as he walked into the South African courthouse Tuesday ahead of his sentencing.

Masipa had a range of options for Pistorius' punishment after convicting him of culpable homicide, or negligent killing, in Steenkamp's death, but acquitting him of murder. Masipa could have issue a suspended sentence and a fine, meaning Pistorius would not have gone to jail. Or she could have sent him to prison for up to 15 years.

Pistorius' lawyers argued for a three-year period of correctional supervision, where the runner would spend periods under house arrest and also perform community service. Prosecutors had asked the judge to send him to prison for at least 10 years.

Pistorius was escorted through crowds of onlookers and into the Pretoria courthouse by police officers wearing blue berets.

The courtroom was packed, reflecting heightened media and public interest ahead of the sentencing. Police officers stood guard in the aisles.

Before proceedings started, Dr. Lore Hartzenberg, a psychologist, held Pistorius' hand and spoke softly to him. Hartzenberg had testified for the defense that Pistorius was a "broken man" after killing his girlfriend and had suffered emotionally and financially.

A Pistorius supporter laid three white roses near Pistorius.

"I just wanted to bestow a little bit of inner happiness on Oscar," said the supporter, who added that she thought he had lost a lot of self-respect.

Outside the courthouse, a man in orange garb carried chains and a large sign that read: "Are certain offenders more equal than other offenders before the law?"