M. Tullius Cicero Pro A. Cluentio 176

[176]
  After his death Sassia, that abandoned woman, immediately began to devise plots against her son. She determined to have an investigation made into the death of her husband. She bought of Aulus Rupilius, whom Habitus had employed as his physician, a slave of the name of Strato, as if she were following the example of Habitus in purchasing Diogenes. She said that she was going to investigate the conduct of this Strato, and of some servant of her own. Besides that, she begged of that young Oppianicus that slave Nicostratus, whom she thought to be too talkative, and too faithful to his master, for judicial examination. As Oppianicus was at that time quite a boy, and as that investigation was being instituted about the death of his own father, although he thought that that slave was a well-wisher both to himself and to his father, still he did not venture to refuse anything. The friends and connections of Oppianicus, and many also of the friends of Sassia herself, honourable men, and accomplished in every sense of the word, are invited to attend. The investigation is carried on by means of the severest tortures. When the minds of the slaves had been tried both with hope and fear, to induce them to say something in the examination, still, compelled (as I imagine) by the authority of those who were present, and by the power of the tortures, they adhered to the truth, and said that they knew nothing of the matter.