This question is seldom asked, but once put, is surprisingly difficult to answer.

Let us be clear from the outset that the nature and extent of Paul's persecuting activity should not be exaggerated. The language of Acts 9:1 is bloodthirsty (‘saul was still breathing threats to slaughter the Lord's disciples’), and there is an allusion in Acts 26:10 to the death penalty. Nevertheless, there is no reason to think that Paul ever shed blood. For one thing, these two passages of Acts belong, I believe, to the latest redactional level of Acts and bring an element into the narrative which was not even implicit in its earlier stages of development. The language which Paul himself employs is not specific, and its vehement tone contributes to a rhetorical effect which Paul no doubt intended. Furthermore, when Paul refers to ‘persecutions’ (διωγμοί) which he himself has suffered (2 Cor. 12:10), it is in a recapitulation of his account of the hardships of many kinds which he has endured for the sake of the gospel (11:2360.), and the only one which he certainly suffered at the hands of fellow Jews was the ‘forty lashes less one’, which he says he received on five occasions (11:24). It is to be presumed that he went no further when he was a persecutor.