A furious Roger Kebble says that Clinton Nassif never told him his son wanted to kill himself as was claimed on the witness stand on Thursday.

The mining tycoon's former security head testified that Kebble"s father "freaked out" when he heard about the assisted suicide plot, and responded by saying his son often threatened to kill himself.

Brett Kebble was gunned down in Melrose in September 2005. Glenn Agliotti is on trial for the murder in the South Gauteng High Court.

Roger Kebble said Nassif's claims were absolute rubbish.

"He is talking absolute rubbish. He did not indicate to me that Brett was about to commit suicide and I don't believe that he did," said Kebble.

He does, however, acknowledge that the security man did visit him once to tell him Brett Kebble was looking for a pill which could arrest one's heart, but that he never mentioned anything about an assisted suicide.

"The next day when I asked him [Brett] he said, 'These guys are idiots, I play games with them,'," said Kebble.

He was enraged by the way his son's murder trial is unfolding, saying the prosecution is clueless.

"This thing has been a bloody shambles and now we have a prosecution who can't even lift their hands. Mr. [Laurance] Hodes is having a bloody ball because there is no opposition there. This case is a mess," said Kebble.

"I am sick and tired of it. I hope the judge has the sense to chuck this whole thing away and start a whole new investigation," said Kebble.

Nassif will return to the witness stand on Friday morning.