What evidence exists to prove that a statement was not freely given and/or denied on the witness stand?

None of the appellants either 'presented evidence to show his statement was not freely given, (or) denied its truth on the witness stand.' (People v. Lara, supra, 67 A.C. at p. 396, 62 Cal.Rptr. at p. 605, 432 P.2d at p. 221.) Rhone, the only appellant to testify in his own behalf, expressly conceded the free and voluntary nature of his extrajudicial statement and the overall accuracy and truthfulness of its contents. That is to say, Rhone testified that he and his codefendants had discussed the robbery in advance and the part each person was to play therein. They had definitely agreed that the robbery would occur on a Friday when the greatest amount of money would be obtainable. He corroborated each of the events described by the prosecution's witnesses. Further, he confirmed the fact that a futile attempt had been made to open the cash register after the shooting.