South African police may have altered evidence and planted weapons after they shot dead 34 striking miners near Lonmin's Marikana mines in August, according to photographic evidence presented at a commission of inquiry into the killings.

Photographs taken by police the night after the shootings show more weapons by the dead bodies than there were in photographs taken immediately after the violence on Aug. 16. Thousands of miners had gathered at hills in Marikana about 94 kilometers (58 miles) northwest of Johannesburg where 34 miners were shot dead by police and 78 wounded in the worst state violence since the end of apartheid in 1994.

South Africa is conducting a commission of inquiry to look into the parties responsible for 46 deaths, including two policemen and two security guards, during nearly six weeks of strikes at the Lonmin Marikana mines.

Video evidence shown Monday also indicated that some of the slain miners may have been handcuffed.

National police commissioner Riah Phiyega said that the commission has launched an investigation into the discrepancies. She said she was presented with evidence that may have suggested one of the crime scenes had been tampered with nearly two weeks ago.

Human rights lawyer George Bizos said the evidence presented at the inquiry clearly indicates an attempt was made to alter the scene.

"The evidence clearly showed there is at least a strong prima facie case that there has been an attempt to defeat the ends of justice," he said. Bizos, who is representing the Legal Resources Centre and Bench Marks Foundation during the inquiry, called on senior police officers in charge of the scene to present evidence.

Crime scene expert Capt. Apollo Mohlaki, who took the night photographs, was questioned during the inquiry Monday. He admitted his photographs showed more weapons around the bodies than those taken earlier, according to the South Africa Press Association. In one set of photos, a man's mangled dead body lies alone in the daylight, and in a picture taken by electric light after dark, there is a panga (machete) under the man's hand.

Mohlaki said he saw the weapon under the man's arm in the photograph he took, but when looking at the day photograph of the same body he said of the weapon: "It is not appearing, I don't see it."

Dali Mpofu, the attorney for the Lonmin miners, entered a video as evidence that showed miners that seemed to be handcuffed. When asked if he saw if any of the dead miners' hands had been bound, Mohlaki said he had not.

"If I am looking at the video there is a person, handcuffed possibly, but on the day I did not observe that," Mohlaki said.

The representative for the police, Ishmael Semenya, had suggested the week before that the integrity of the crime scene could have been compromised by the presence of paramedics, according to SAPA.

"We will hear evidence that paramedics asked that weapons be removed so they could do their work," said Semenya.

On Tuesday, the commission saw photographs of the security guards' bodies, who were among those killed before the Aug. 16 shootings. The photographs showed one of the guards with his tongue cut out while the legs of the other security official were visible in the charred remains of a security vehicle torched by the protesters, according to SAPA. Another photograph showed a group of marchers fleeing with a shotgun stolen from the security guards, it said.

The inquiry began last month and is expected to continue for four months, investigating the roles played by police, miners, unions and Lonmin in the August deaths. Strikes at Lonmin spread to other mining sectors last month, and a deal reached with Lonmin miners that saw workers getting a pay increase of up to 22 percent has workers at other mines demanding similar deals.

Gold Fields said Tuesday that thousands of employees returned to work at the company's South Africa KDC East mine ending a 23-day strike. All three of its mines in South Africa are now back in production, it said. Gold Fields, which is one of the world's top producers of gold, had dismissed 8,100 employees in October for participating in illegal strikes, however it says a deal reached with the National Union of Mineworkers saw a vast majority of those workers reinstated.

The NUM said Tuesday that the 12,000 miners fired from platinum mining company Anglo American Platinum in Rustenburg for staging illegal strikes since September had still not returned to work, and negotiations were underway.