Is a police officer required to preserve handwritten notes in the course of questioning a criminal defendant?

In People v. Jones, supra, 145 Cal.App.3d 751, 753-754, 193 Cal.Rptr. 663, the court decreed "... a police officer must take reasonable precautions to preserve for trial his original handwritten notes made in the course of interrogating a criminal defendant unless the interrogation is tape recorded and the tape is preserved for trial. 'Reasonable precautions' mean a good-faith attempt to adhere to systematic procedures designed to preserve the notes for trial. If the officer fails to comply with this rule, the sanction will be suppression of all testimony by the officer concerning any statements made by the defendant during interrogation, assuming the requisite showing of materiality has been made."