Began (arxamenos). Not pleonastic here, but graphically showing how Peter began at the beginning and gave the full story of God’s dealings with him in Joppa and Caesarea.
Expounded (exetitheto). Imperfect middle of ektithēmi, to set forth, old verb, but in the N.T. only in Acts (Act 7:21; Act 11:4; Act 18:26; Act 28:23), a deliberate and detailed narrative “in order” (kathexēs). Old word for in succession. In the N.T. only in Luk 1:2; Luk 8:1; Act 3:24; Act 11:14; Act 18:23. Luke evidently considered this defence of Peter important and he preserves the marks of authenticity. It came originally from Peter himself (Act 11:5, Act 11:6, Act 11:15, Act 11:16). “The case of Cornelius was a test case of primary importance” (Page), “the first great difficulty of the early Church.” Part of the story Luke gives three times (Act 10:3-6, Act 10:30-32; Act 11:13.). See the discussion chapter 10 for details given here.