Title: Preservation of Evidence in Criminal Cases | Nolo
Headings: Preservation of Evidence in Criminal Cases
Preservation of Evidence in Criminal Cases
Law enforcement officers and prosecutors have a duty to preserve certain kinds of evidence. Learn what they have to keep, and what happens when they don't keep it.
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What Kind of Evidence Must Be Preserved?
Alibi evidence
Other kinds of evidence
Who Has to Preserve Evidence?
Private people exempted
What Happens If Evidence Is Lost or Destroyed?
Proving materiality
Proving bad faith
Remedies

Content: The duty to preserve evidence begins once any state agency or actor has gathered and taken possession of evidence as part of a criminal investigation. What Kind of Evidence Must Be Preserved? Law enforcement doesn’t need to preserve all evidence it collects. The duty to preserve extends only to evidence that might be expected to play a significant role in the suspect’s defense: “ material” and “exculpatory” evidence. Material evidence is important evidence that’s directly relevant to an issue in the defendant’s case. Exculpatory evidence is evidence favorable to the defendant in that it clears or tends to clear him of guilt. Alibi evidence
Exactly what evidence is material and exculpatory depends upon the circumstances of the case. But alibi evidence is virtually always material and exculpatory; it includes witness statements that place the defendant somewhere other than the scene of the crime and forensic evidence (like DNA) that tends to show that the defendant couldn’t have committed the crime.