That phrase sounds a little like the Roman practice of torturing a slave before his/her testimony can be accepted in court. It was a couple years ago, but one thread I was researching about mutilation of slaves took me to Roman laws of justice in Justinian's Digest. These legal decisions often had roots several hundred years previous.
I suppose even slaves or freedmen who offer testimony that exonerates a master must be tested by application of torture. This might be something a dedicated slave might be willing to do for a beloved master under suspicion. If I remember correctly, even freedmen who had been granted citizenship, but remained within his former master's household (usually restricted to the masters home), were subject to interrogation by torture. Consider a Paul who was part of a patron's household (household codes, etc.) and willing to give exonerating evidence. If so does that mean Paul was a slave, or a former slave emancipated by any number of methods possible? I would suggest Herod Agrippa at the time he was under scrutiny for his own ambitions, just before he was banished.
Wikipedia wrote:Josephus relates that Herodias, jealous at Agrippa's success, persuaded Antipas to ask Caligula for the title of king for himself. However, Agrippa simultaneously presented the emperor with a list of charges against the tetrarch: allegedly, he had conspired against Tiberius with Sejanus (executed in 31 AD) and was now plotting against Caligula with Artabanus. As evidence, Agrippa noted that Antipas had a stockpile of weaponry sufficient for 70,000 men. Hearing Antipas' admission to this last charge, Caligula decided to credit the allegations of conspiracy. In the summer of 39 AD, Antipas' money and territory were turned over to Agrippa, while he himself was exiled. The place of his exile is given by Josephus' Antiquities as in Spain. Caligula offered to allow Herodias, as Agrippa's sister, to retain her property. However, she chose instead to join her husband in exile.
Antipas died in exile.
Another possibility is related to how Lucian understood Peregrinus Proteus to have a death wish - by fire. Could Paul have had a similar death wish. I believe I have seen another thread recently (on reddit) asking whether Paul was suicidal.