What is the test for determining whether a defendant has been convicted of a prior criminal offence and therefore must proceed further to determine the conduct underlying the conviction?

further" to determine the conduct underlying the conviction. ( People v. Guerrero(1988) 44 Cal.3d 343, 355, 243 Cal.Rptr. 688, 748 P.2d 1150.) It is equally settled that the record of conviction to which the trier of fact may look includes the transcript of the preliminary hearing. ( People v. Reed(1996) 13 Cal.4th 217, 220, 52 Cal.Rptr.2d 106, 914 P.2d 184 ( Reed ); see maj. opn., ante, at 226 Cal.Rptr.3d at p. 385, 407 P.3d at p. 60.) The court here reviewed the preliminary hearing transcript and determined that defendant's prior conviction was a serious felony and thus a strike under the "Three Strikes" law. (Maj. opn., ante, at 226 Cal.Rptr.3d at pp. 380381, 382383, 407 P.3d at pp. 5657, 5758.)