What is the Miranda rights of a material witness?

"Under some narrow circumstances, sometimes called the `public safety' or `rescue' exceptions, compliance with Miranda is excused where the purpose of police questioning is to protect life or avoid serious injury and the statement is otherwise voluntary. [Citations.]" (People v. Panah (2005) 35 Cal.4th 395, 471.) In some instances, "`"where the possibility of saving the life of a missing victim exists, noncoercive questions may be asked of a material witness in custody even though answers to the questions may incriminate the witness."'" (People v. Davis (2009) 46 Cal.4th 539, 593-594.) In reviewing whether there was such an emergency and if a victim could be saved, we look at "objective facts known to law enforcement." (Id. at p. 593.)