Strikers were armed when they gathered on a hilltop near Lonmin's Marikana mine in North West, where police opened fire on them, a senior officer testified on Monday.
Brigadier Jacobus van Zyl, head of Potchefstroom detectives, told the Ga-Rankuwa Magistrate's Court the striking workers held an illegal protest before the deadly clash.
They gathered on the hill near the mine, wielding sharpened rods.
Van Zyl was called by the prosecution team to testify that investigations were still underway, and that the 260 people arrested after the shooting should stay in custody.
Thirty-four people died in the August 16 shooting and 78 were wounded. Ten people, including two policemen and two security guards, were killed in the preceding week.
Those arrested appeared in batches in the Ga-Rankuwa Magistrate's Court on Monday, on charges ranging from murder to public violence.
Van Zyl said the police had yet to verify their addresses and check their fingerprints for criminal records and previous convictions.
So far, the investigating teams had found that four of them had pending criminal cases, but the probe was ongoing.
Van Zyl said the process of verifying their home addresses had not ended.
He said Lonmin had indicated they would not be welcome back at work, and he did not know whether they would continue to stay at the mine's hostels. He said police had tried to negotiate with the workers on the hilltop to disperse peacefully, and to "leave behind the dangerous weapons they were carrying".
Security was tight at the Ga-Rankuwa Magistrate's Court when the first batch of mine workers were brought into court before 2pm. Dozens of police officers accompanied them into court. Some of the miners held hands when they walked into the courtroom in single file.
Benches on the left-hand side of the court were reserved for the miners. The media and a few other people were on the right.
Suspended ANC Youth League spokesman Floyd Shivambu and secretary-general Sindiso Magaqa were among those in attendance.
In the morning, two groups of protesters, one of women and another of men, merged outside the court entrance, demanding the mineworkers' release.
They waved placards, some of which read: "Drop the charges, amnesty for all strikers arrested", "The real criminals are SAPS and Lonmin", and "Phiyega you are a criminal".
The mineworkers were brought to court in trucks escorted by the police's tactical response team members. The convoy drove past the protesters at the entrance around 10am.
The miners peered through the trucks' small windows, and banged on the sides of the vehicles. As they made their way onto the court premises, the protesters sang, chanted and wailed.
The main entrance to the court had been sealed off by police officers bearing shields and wearing helmets. Two Nyala armoured vehicles were parked nearby.
The State asked for a seven-day postponement. It said the ongoing investigations were wide and complex. The investigation would allow the State to unravel what had happened at the mine, and additional charges would be laid later.
The State said the probe would be complicated by the fact that some of the miners were immigrants.