By TJ Strydom and Tanisha Heiberg

PRETORIA (Reuters) - Oscar Pistorius must pay for the crime of murdering his girlfriend Reeva Steenkamp, which has devastated her family, her father told a South African court on Tuesday.

The 29-year-old Paralympian gold medalist faces a minimum 15-year jail term after his manslaughter conviction for the 2013 killing, for which he originally received a five-year sentence, was upgraded on appeal.

Called to testify by the lead state prosecutor in Pistorius's sentencing hearing, a tearful and trembling Barry Steenkamp said forgiving the runner was very hard.

"It just devastated us, I ended up having a stroke... I just don't wish that to anybody in this world," the 73-year-old said. "He has to pay for his crime."

Steenkamp said he and wife June had relied financially on their daughter, and he had hurt himself to try to relive the pain that his daughter went through: "I jabbed myself with needles."

He asked the court to allow pictures of his daughter to be shown to the world as a deterrent to would-be killers.

Jonathan Scholtz, a psychologist called by Pistorius' lawyer, told the court on Monday -- the first day of the hearing -- that the athlete was "a broken man" on medication for depression, anxiety and insomnia who should be hospitalized and not jailed.

But prosecutor Gerrie Nel said Pistorius has shown no remorse for shooting and killing Steenkamp when he fired four shots through a locked toilet door in his Pretoria home.

Nel also said he had had temper tantrums while serving his sentence.

'TANTRUMS'

The case has prompted a fierce debate in a country beset by high levels of violent crime against women. Some rights groups have said the white athlete has received preferential treatment.

Charlotte Mashabane, an assistant health manager at the prison where Pistorius was held for a year, told the court on Tuesday he "threw tantrums" while in prison and she felt threatened by him.

Mashabane said Pistorius became angry when she declined to change his approved medication for medication supplied by his family, and that he had thrown some medicine on her table.

Mashabane also said there was no report of Pistorius being assaulted while in prison, as Scholtz had asserted.

Pistorius lawyer Barry Roux disputed Mashabane's testimony, saying she was changing it to cast his client in a bad light.

Earlier on Tuesday Ebba Gudny Gudmundsdottir, from Iceland, described the runner as an inspiration to her 11-year-old son, who has a similar disability to Pistorius.

The lower part of the athlete's legs were amputated when he was a baby, and he is known as "Blade Runner" for the carbon-fibre prosthetics he wore when racing.

Pistorius reached the pinnacle of his fame in London 2012 when he became the first double amputee to run in the Olympics, reaching the 400 meters semi-finals.

Gudmundsdottir told the court Pistorius often visited her family in Iceland and her family traveled to Manchester to see Pistorius race. "It was an inspiration for him (her son) to see Oscar and the others run," she said.

Marius Nel, a pastor, said Pistorius had worked at his church's charity, training school children in athletics. "Feedback from the schools was very positive," he said.

At his original trial, Pistorius had argued he mistook Reeva Steenkamp for an intruder.

His manslaughter conviction was upgraded to murder after an appeal heard by the Supreme Court, which ruled in March that Pistorius had exhausted all his legal options.

The original trial judge, Thokozile Masipa, is also presiding at the sentencing hearing, at Pretoria High Court.

(Writing by James Macharia; editing by John Stonestreet)