In In re Ibarra (1983) 34 Cal.3d 277, the California Supreme Court rejected the notion that a package-deal plea is inherently coercive. (Ibarra, at pp. 283-284, 286-287.) It explained that normally a court may properly rely on a validly executed waiver form in determining the voluntariness of a guilty plea. (Ibarra, at p. 281.) However, "when a defendant pleads guilty pursuant to a 'package-deal' arrangement, the trial court has a duty to conduct further inquiry into the voluntariness of the plea: although such a bargain is not per se coercive, it may be so under a totality of the circumstances." (Ibarra, at pp. 281-282.) Under Ibarra, the trial court must make a series of inquiries. First, it "must determine whether the inducement for the plea is proper. The court should be satisfied that the prosecution has not misrepresented facts to the defendant, and that the substance of the inducement is within the proper scope of the prosecutor's business. The prosecutor may also have a reasonable and good faith case against the third parties to whom leniency is promised. Second, the factual basis for the guilty plea must be considered. If the guilty plea is not supported by the evidence, it is less likely that the plea was the product of the accused's free will. The same would be true if the 'bargained-for' sentence were disproportionate to the accused's culpability. Third, the nature and degree of coerciveness should be carefully examined. Psychological pressures sufficient to indicate an involuntary plea might be present if the third party promised leniency is a close friend or family member whom the defendant feels compelled to help. 'The voluntariness of a plea bargain which contemplates special concessions to another -especially a sibling or a loved one - bears particular scrutiny by a trial or reviewing court conscious of the psychological pressures upon an accused such a situation creates.' If the defendant bears no special relationship to the third party promised leniency, he may nevertheless feel compelled to plead guilty due to physical threat. For example, if the third party had made a specific threat against defendant if he refused to plead guilty, the plea is likely to be involuntary. On the other hand, if the defendant merely thought . . . that his codefendant would attack him if he did not plead guilty, sufficient coercive factors may not be at play. Fourth, a plea is not coerced if the promise of leniency to a third party was an insignificant consideration by a defendant in his choice to plead guilty. For example, if the motivating factor to plead guilty was the realization of the likelihood of conviction at trial, the defendant cannot be said to have been 'forced' into pleading guilty, unless the coercive factors present had nevertheless remained a substantial factor in his decision." (Ibarra, supra, 34 Cal.3d at pp. 288-290.) Ibarra makes clear that these factors are not exclusive; that other factors, such as the defendant's age, that may be relevant can and should be taken into account. (Ibarra, supra, 34 Cal.3d at p. 290.) The court also emphasized that a guilty plea under a package-deal plea bargain will not be set aside merely because the trial court failed to undertake the aforementioned totality of the circumstances inquiry. (Id. at p. 290, fn. 6.) Rather, the defendant must show the error prejudicial; i.e. he "must allege and prove that his plea of guilty was involuntary under the Ibarra standards . . . and should not have been accepted by the trial court." (Id. at p. 290.)