* Pretoria court hears grisly evidence of Steenkamp killing
* Second witness testifies she heard argument
* Judge warns media over leaked photo (Recasts, adds details)
By Ed Cropley
PRETORIA, March 4 (Reuters) - Oscar Pistorius buried his head in his hands and wiped away tears after a South African court on Tuesday heard grisly details of the killing of his girlfriend, the first sign of emotion from the track star in his two-day murder trial.
The Olympian and Paralympian has been largely impassive during the trial for the murder of model and law graduate Reeva Steenkamp in his suburban Pretoria home on Valentine's Day last year. Pistorius has pled not guilty, saying he shot Steenkamp through a toilet door after mistaking her for an intruder.
He leaned forward in the dock and clasped his head between his hands as lead defence lawyer Barry Roux read out details from the post mortem, including that "some fragments of the bullet" were removed from the 29-year-old's head.
Roux also heaped scorn on the testimony of neighbour Michelle Burger, who said she heard a scream fade away after the shots, saying that Steenkamp would have "dropped immediately" due to a bullet in the head.
Steenkamp was declared dead at the scene after being hit in the head, arm and hip from three bullets from a 9 mm pistol.
Pistorius, dressed a dark suit and tie, later appeared to wipe away tears.
The trial, which could see one of global sports' most admired figures jailed for life, has drawn comparisons with the high-profile murder trial of American football star and actor O.J. Simpson two decades ago.
Burger broke toward the end of her own testimony, following an angry exchange with Roux, who had sought to show she had mistaken the screams of agitated Pistorius for that of a woman.
The court also heard from a another neighbour, Estelle van der Merwe, who testified that she heard what sounded like an argument early on the morning Steenkamp was killed.
"From where I was sitting it seemed like two people were having an argument but I couldn't hear the other person's voice," she said through an Afrikaans language interpreter.
The judge also warned the media to behave after a local television station leaked a photo of the state's first witness, who had asked that her image not be broadcast, another delay to a trial that has already been hampered by late starts and problems with court interpreters.
Judge Thokozile Masipa ordered an investigation after broadcaster eNCA showed a photo of Burger during the audio broadcast of her second day of emotional testimony.
While the trial is being televised live, a previous court order had ruled witnesses must give their consent to be filmed.
Burger, a university lecturer who testified on Monday that she heard "bloodcurdling" screams from a woman followed by gun shots, had not consented to being filmed and only the audio of her testimony was being broadcast.
The station accompanied the audio feed of her testimony on Tuesday with a picture of her. After prosecutor Gerrie Nel pointed out the leak, Masipa called for a brief adjournment.
"I am warning the media, if you do not behave, you are not going to be treated with soft gloves by this court," Masipa, herself a former journalist, said when the court resumed.
The station's head of news apologised, saying in a statement it was a "bad judgement call" to use the photo.
Masipa has also restricted the media from publishing photos of witnesses who have not consented to be filmed.
A separate South African court ruled last month that the trial should be televised, saying it was vital for impoverished South Africans who feel ill-treated by the justice system to get a first-hand look at the proceedings.
The start of the trial was delayed by 90 minutes on Monday due to a problem with the Afrikaans language interpreter. Burger began her testimony in Afrikaans but later switched to English after disagreeing with the interpreter's translation of some words. (Writing by David Dolan; Editing by Angus MacSwan)