Convicted RSA triple murderer William Bell competed in a formal debate in Paremoremo Prison last week against a team of Telecom executives, and the inmates won.
The training exercise was designed to improve the communication and leadership skills of the executives, while at the same time teaching the inmates to accept other points of view.
The prison team successfully argued that capital punishment should be reintroduced because it would cut the number of inmates who left prison only to re-offend again.
Telecom spokesperson Ken Brophy told Herald on Sunday that Bell, who is serving a 30-year prison sentence for the RSA killing spree in Auckland in 2001, had been "very articulate" on the debating team.
He said the other prisoners were also "amazing, impactful and informative".
Mr Brophy said the Telecom executives took part in the training programme -- run by New Zealand-born international leadership guru John Wareham -- to help them communicate in a more compelling way.
"If us putting what we learned into practice helps these guys to...be more positive people in society, then we are willing to help," Mr Brophy told Herald on Sunday.
But the training programme has angered Sensible Sentencing Trust founder Garth McVicar.
"It horrifies me for the families involved that William Bell killed their loved ones and he is treated with the respect of being involved in a debate," he told Herald on Sunday .
"These guys are in there to be punished and I can't find the words to describe how I feel without swearing."
Tai Hobson, the husband of RSA murder victim Mary Hobson, said he hoped the programme would rehabilitate Bell.
"Something like that [training programme] may be worthwhile," he said.
"I'm not saying it will be, but it might give him some incentive to pull himself together."
At the end of the debate the executives and prisoners talked about last week's rugby league match over cake, crackers and dip.