WILLEM OOSTHUIZEN and THEO JACKSON, both wearing jackets and ties, were also found guilty of kidnap, intimidation and assault with intent to do grievous bodily harm.
They had pleaded not guilty over the incident last year in the eastern province of Mpumalanga, saying they only intended to scare Mlotshwa after he allegedly stole copper cables from their farm.
Two clips of footage taken on their mobile phones showed the assailants shoving Mlotshwa down into the wooden coffin and pressing the lid closed with their boots as he begged for his life.
Activists from rival political parties, including the ruling African National Congress and the main opposition Democratic Alliance, rallied outside court and attended each day of the trial.
