What are some examples of prosecutorial lack of due diligence?

There is no need to dissect the facts of each of the cases cited by defendants illustrating prosecutorial lack of due diligence. Suffice it to say, the facts are easily distinguished. For example, in People v. Roldan (2012) 205 Cal.App.4th 969, the prosecution knew, but did not disclose to the defense or take a single precautionary step, that a material witness would be deported at the conclusion of the preliminary hearing. The prosecution did not impress on the witness the importance of staying in touch with investigators; nor did it seek a section 1332 material witness hold. Needless to say, the prosecution was well aware the material witness would be unavailable for trial and yet it sat idle.