"You had relations with [former police minister] Mr Nathi Mthethwa, you were both in the ANC national executive of the ANC, as well as with [ANC secretary general] Gwede Mantashe," said Dali Mpofu, for the wounded and arrested Marikana miners.
"You were a non-executive director of Lonmin. If you look at that web of relationships you will accept that you were caught in a cesspool of incestuous relationships in relation to the [Marikana] players."
"Mr chairman, I do take exception to a question that seems to suggest that my relation with my organisation, the African National Congress, is incestuous," he said.
"Similarly, Mr Chairman, I also take exception to a suggestion that my relationship with the secretary general of the ANC, and all the other colleagues, is incestuous."
Mpofu responded: "Yeah, that might well be."
Commission chairman retired judge Ian Farlam said "incestuous" was an "unhappy word" which should be withdrawn.
"You should spell out what the nature of the conflict was. Put to the witness clearly what the conflict was. Don't use objectionable adjectives," Farlam said.
Mpofu responded: "I will try and restrain myself."
The commission is investigating the deaths of 44 people during strike-related violence at Lonmin's platinum mining operations at Marikana, near Rustenburg in the North West, in August 2012.
Thirty-four people, mostly striking mineworkers, were shot dead in a clash with police, over 70 were wounded, and over 250 arrested on August 16, 2012. Police were apparently trying to disarm and disperse them.
In the preceding week, 10 people, including two policemen and two Lonmin security guards, were killed.
On Tuesday, Mpofu said Ramaphosa's responsibilities at Marikana went beyond fiduciary duties as a non-executive director of Lonmin.
"Of the parties you say should share the responsibility, you were associated with [the] Lonmin board and management, you were a shareholder, the SA Police Service, the government," said Mpofu.
Ramaphosa said he was not in government [at the time].
Mpofu retorted: "You were not in government but you were exchanging telephone calls with people in government.
"You were a senior member of the ANC".
Mpofu suggested Ramaphosa was criminally liable for the Marikana events.
"For me to motivate for that recommendation to be made, I am going lay the basis in this discussion with you. The first basis is your actions or non-actions," he said.
"The other basis is what we lawyers call the causality. That is the connection between what you did and the consequences thereof. In this case, the consequences are the death and injuries of mineworkers."