(CNN) -- He's known as the "bull dog" in South Africa's legal circles, and just days in to Gerrie Nel's merciless cross-examination of Oscar Pistorius, it's easy to see why. The veteran state prosecutor's relentless grilling of Pistorius -- on trial for the murder of his girlfriend Reeva Steenkamp on Valentine's Day last year -- has riveted people around the world to their TV sets, and has sparked a debate about whether Nel's no-holds-barred tactics have crossed the line. Nel had to wait weeks to take on Pistorius, but has wasted no time since he got the chance late on Tuesday. At various times Nel has called the 27-year-old a liar, implied that Pistorius was pretending to be too emotional to testify, reduced him to tears, and laughed at him for failing to recall the answer to one of Nel's questions as the prosecutor ruthlessly tore into various aspects of his testimony.
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Oscar Pistorius trial prosecutor Gerrie Nel known for no-holds-barred approach to witnesses
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Nel shocked courtroom by showing graphic photo of deceased Reeva Steenkamp
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Some observers say Nel stepped over the line; others say Nel is just doing his job
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Phelps: State has little evidence to disprove Pistorius' case that he is innocent of murder charge
"@placeholder has a responsibility to protect the dignity of the deceased and the victim's family," Phelps said.
Nel has infuriated quite a few opposing lawyers over the course of his career, @placeholder says, but he has long had a reputation for being incorruptible and impossible to intimidate.