They believed, to be fair to them, that they had passed a just sentence.

Blinded by prejudice and falsehood, and maddened by the dreadful losses their people had suffered during the past few days at the hands of a devilish savage, they believed that I was the instigator of those losses, one who ought to die.

Indeed, all, or nearly all the Boers were persuaded that Dingaan was urged to this massacre by the counsels of Englishmen.

The mere fact of my own and my servant's miraculous escape, when all my companions had perished, proved my guilt to them without the evidence of Pereira, which, being no lawyers, they thought sufficient to justify their verdict.
Still, they had an uneasy suspicion that this evidence was not conclusive, and might indeed be rejected in toto by a more competent court upon various grounds.

Also they knew themselves to be rebels who had no legal right to form a court, and feared the power of the long arm of England, from which for a little while they had escaped.