Can a police purpose justify a lengthy delay in presenting evidence to the district attorney?

However, "[n]egligence on the part of police officers in gathering evidence or in putting the case together for presentation to the district attorney, or incompetency on the part of the district attorney in evaluating a case for possible prosecution can hardly be considered a valid police purpose justifying a lengthy delay which results in the deprivation of a right to a fair trial." (Penney v. Superior Court, supra, 28 Cal.App.3d at p. 953, 105 Cal.Rptr. 162.)