Ahead of a judge's decision on whether to release Oscar Pistorius on bail, South African police on Thursday appointed a new chief detective in the murder case, replacing a veteran police officer who was himself charged with attempted murder.

The sensational twist in the state's troubled investigation fuelled growing public fascination with the case against the double-amputee Olympian, who is charged with premeditated murder in the shooting death of his girlfriend, Reeva Steenkamp, in the early hours of Valentine's Day.

Pistorius, a sporting icon and source of inspiration to millions until the shooting a week ago, is backed by a high-powered team of lawyers and publicists. The abruptness of his fall, and its gruesome circumstances, have gripped a global audience and put South Africa's police and judicial system under the spotlight.

The man at the centre of the storm sat in the dock during his bail hearing, mostly keeping his composure in contrast to slumped-over outbursts of weeping and sobbing on previous days in court. In front of Pistorius, defence lawyer Barry Roux pounced on the apparent disarray in the state's case, laying out arguments that amounted to a test run for the full trial yet to come.

Investigating officer Hilton Botha has been removed from the case amid news he faces attempted murder charges in connection with a 2011 incident in which shots were fired at a minibus taxi. (Themba Hadebe/Associated Press)

Roux pointed to what he called the "poor quality" of the state's investigation and raised the matter of intent, saying Pistorius and Steenkamp had a "loving relationship" and the Olympian therefore had no motive to plan her killing.

Pistorius, 26, said he mistook Steenkamp for an intruder when he shot her through a locked door in a bathroom in his home.

Prosecutors believe the shooting happened after the couple got into an argument, and prosecutor Gerrie Nel painted a picture of a man he said was "willing and ready to fire and kill."

Much of the drama Thursday, however, happened outside the courtroom as South African police scrambled to get their investigation on track.

In a news conference at a training academy, National Police Commissioner Riah Phiyega said a senior detective would gather a team of "highly skilled and experienced" officers to investigate the killing of 29-year-old Steenkamp, a model and budding reality TV contestant.

The decision to put police Lt. Gen. Vinesh Moonoo in charge came soon after word emerged that the initial chief investigator, Hilton Botha, is facing attempted murder charges, and a day after he offered testimony damaging to the prosecution.

Botha acknowledged Wednesday in court that nothing in Pistorius' version of the fatal shooting of Steenkamp contradicted what police had discovered, even though there have been some discrepancies. Botha also said that police had left a 9 mm slug in the toilet and had lost track of allegedly illegal ammunition found in Pistorius' home.

"This matter shall receive attention at the national level," Phiyega told reporters soon after the end of proceedings in the third day of Pistorius' bail hearing.

Bulewa Makeke, spokeswoman for South Africa's National Prosecuting Authority, said the attempted murder charges had been reinstated against Botha on Feb. 4. Police say they found out about it after Botha testified in Pistorius' bail hearing Wednesday.

Botha and two other police officers had seven counts of attempted murder reinstated against them in relation to a 2011 shooting incident. Botha and his two colleagues allegedly fired shots at a minibus they were trying to stop.

Makeke indicated the charges were reinstated against Botha because more evidence had been gathered. She said the charge against Botha was initially dropped "because there was not enough evidence at the time."

Pistorius seeking bail

On Thursday, Chief Magistrate Desmond Nair asked the defence of Pistorius' bail application: "Do you think there will be some level of shock if the accused is released?"

Defence lawyer Roux responded: "I think there will be a level of shock in this country if he is not released."

Prosecutor Nel suggested signs of remorse from Pistorius had nothing to do with whether he planned to kill his girlfriend.

"Even if you plan a murder, you plan a murder and shoot. If you fire the shot, you have remorse. Remorse might kick in immediately," Nel said.

As Nel summed up the prosecution's case opposing bail, Pistorius began to weep in the crowded courtroom, leading his brother, Carl Pistorius, to reach out and touch his back.

"He [Pistorius] wants to continue with his life like this never happened," Nel went on, prompting Pistorius, who was crying softly, to shake his head. "The reason you fire four shots is to kill," Nel persisted.

Earlier Thursday, Nair questioned Botha over delays in processing records from phones found in Pistorius' house following the killing of Steenkamp.

"It seems to me like there was a lack of urgency," Nair said as the efficiency of the police investigation was questioned.

Botha is himself to appear in court in May to face seven counts of attempted murder. Botha was dropped from the case but not suspended from the police force, Phiyega said, and could still be called by defence lawyers at trial.

Pistorius, in the same grey suit, blue shirt and grey tie combination he has worn throughout the bail hearing, stood ramrod straight in the dock, then sat calmly looking at his hands.

Roux said an autopsy showed that Steenkamp's bladder was empty, suggesting she had gone to use the toilet. Prosecutors say Steenkamp had fled to the toilet to avoid an enraged Pistorius.

"The known forensics is consistent" with Pistorius' statement, Roux said, asking that bail restrictions be eased for Pistorius.

But the prosecutor said Pistorius hadn't given guarantees to the court that he wouldn't leave the country if he was facing a life sentence. Nel also stressed that Pistorius shouldn't be given special treatment.

"'I am Oscar Pistorius. I am a world-renowned athlete.' Is that a special circumstance? No." Nel said. "His version [of the killing] is improbable."

Nel said the court should focus on the "murder of the defenceless woman."

Botha testified Thursday that he had investigated a 2009 complaint against Pistorius by a woman who said the athlete had assaulted her. He said that Pistorius had not hurt her and that the woman had actually injured herself when she kicked a door at Pistorius' home.