Two police detectives visited the offices of the trade union on Monday this week to discuss obtaining further affidavits, deputy general secretary Dirk Hermann confirmed on Thursday.
Last month Solidarity laid criminal charges against the expelled ANC Youth League leader and the matter was transferred to Springs police. Hermann said he believed a team from the Hawks and police detectives were working on the case.
"The police officers wanted some new affidavits from us," said Hermann. "Our members want to work and [Malema] said he is going to lead a mining revolution. It is quite clear it will mean violence."
Solidarity said it had more than 20 000 members working in the mines and one of its members was set alight in the early stages of the Marikana violence. Another had his jaw broken while a third was hospitalised for injuries he sustained during the unrest at the mines.
"The threats to our members are very real and there is no political agenda here," said Hermann. "People have been threatened and they fear for their safety."
Malema was back visiting the mines this week, this time speaking to striking miners at the Meloding stadium in Virginia in the Free State. During this visit, Malema reportedly said unions had become sell-outs. "You have a right to stand on your own."
The National Union of Mineworkers (NUM) had been compromised, the Times quoted him as telling the miners. "It is now NUM Pty Ltd, a private company", he said.
Malema told the Mail & Guardian he did not believe that he had been inciting the miners.
"I made a political analysis when I said that NUM was compromised because of its business interests. What was inciteful about it?"
NUM spokesperson Lesiba Seshoka could not be reached for comment.
Hermann said that under tense situations, like the ones playing out at the mines, Malema's actions had threatened its members' safety and security of employment.
"Malema's actions – by calling the mines to be made ungovernable, for a mining revolution and for strike action – contribute to the instigation of illegal strike action and also prolongs ongoing illegal strikes," he said.
During the recent Lonmin strike, Solidarity's members were unable to go to work, due to fear for their safety.
Solidarity believes the actions of Malema contribute to the labour unrest in the mines and criminal prosecution might assist in stopping him from further similar actions in future.
In his affidavit handed to police, Hermann said when Malema called for a nationwide strike and for a serious revolution, he knew public violence and intimidation stemmed from strike action.
"His calls for a nationwide strike and for a serious revolution in the mining industry is therefore incitement to public violence and intimidation," he said.
Incitement is punishable by law, said Hermann, and it was Solidarity's opinion the incitement by Malema had already resulted or may result in crimes. These should be viewed in an "extremely serious light".
While Solidarity accused him of incitement for saying he wanted to start a mining revolution, Malema said he did not know this union. By saying he wanted to start a mining revolution, he had simply meant radical change was needed.
"We have often called for a South African revolution, but that does not mean we are calling civilians to arms. It means radical change is needed," he said.