In habeas corpus appeal cases in connecticut court cannot disturb the underlying facts found by the habeas court unless they are clearly erroneous, but our review of whether the facts as found by the habeas court constituted a violation of the petitioner's constitutional right to effective assistance of counsel is plenary. Johnson v. Commissioner of Correction, 36 Conn. App. 695, 700, 652 A.2d 1050, cert. denied, 233 Conn. 912, 659 A.2d 183 (1995). For the petitioner to prevail on his claim of ineffective assistance of counsel, he must establish both that his counsel's performance was deficient and that there is a reasonable probability that, but for counsel's mistakes, the result of the proceeding would have been different. Strickland v. Washington, 466 U.S. 668, 694, 104 S. Ct. 2052, 80 L. Ed. 2d 674 (1984); Bunkley v. Commissioner of Correction, 222 Conn. 444, 445, 610 A.2d 598 (1992).