Re: What criminal charges would a person who buried an overdosed friend face.

If the character that buried the deceased provided the heroin, that they both used to shoot up with, he/she could face murder charges. It's a crime to conceal a deceased person and using that person's identity to make charges on their accounts could be theft from the creditors.

Re: What criminal charges would a person who buried an overdosed friend face.

Um...interesting. Well, there are too many details missing to develop a complete analysis. Therefore, I set aside the issue whether the surviving heroin user has any culpability for the death of his partner but it appears that there would be criminal liability for burying his body in the desert. Improper disposal of human remains is a misdemeanor. Your character may also be liable for assuming the dead man's identity if he does that with a criminal or fraudulent purpose. Whether that would constitute a felony or misdemeanor will depend on the amount of the loss occasioned by assuming that identity.

Burying the body without notifying next of kin is such extreme and outrageous conduct that the dead man's next of kin could maintain a successful action for intentional infliction of emotional distress. This could result in the imposition of punitive damages in a civil action.

Possibly murder

This is similar to a hypothetical, so the answer will be speculation. If the person who assumed the other's identity supplied the herion to the person who died, then the District attorney may prosecute under a murder statute. Everything else is secondary in my opinion.