Correct.<quoted text>He allegedly took an active part in the martyrdom of Stephen.
Note that the persecutions of the time were NOT against Christians. They were against Jews. Esp. Jewish sects that were seen as trouble makers. The Christians were just another Jewish sect just like the Westboro Baptists are just another Christian sect.
It has been argued that following his conversion Paul's main goal was to create an identity for Christians as separate from Judaism in order to keep them from being persecuted. A goal it took 300 years to accomplish.