On Monday Mr X was accused of lying by advocate Heidi Barnes, for the Association of Mineworkers and Construction Union (Amcu).
Mr X has previously told the inquiry that Amcu president Joseph Mathunjwa visited protesting Marikana miners on the night of 14 August 2012.
"We will argue that Mr Joseph Mathunjwa's affidavit together with objective evidence established that he could not have been at the koppie (hill) on 14 August 2012.
"Your evidence in this regard is false and must be rejected," Barnes said.
Mr X maintained that Mathunjwa spoke to a workers' leader, Xolani Nzuza, on 14 August 2012, asking for permission to address the miners.
The witness, who cannot be identified, was testifying via a video link to protect his identity as he says he fears for his life.
Dali Mpofu, SC, for the injured and arrested Marikana miners, questioned Mr X's mental state.
"I am still listing the reasons why I am going to say your evidence should be discarded as a whole. I am putting this in the kindest possible way - you are in a bad mental and emotional state," said Mpofu.
The inquiry, which is led by retired judge Ian Farlam, is investigating the deaths of 44 people during strike-related violence at Lonmin's platinum mining operations at Marikana.