Reversal of conviction for failure to give a missing evidence instruction
Law enforcement officers generally are obliged to preserve evidence from an alleged scene of a violent crime, and not to contaminate the scene before the evidence is collected. Police should collect and preserve evidentiary samples in sufficient quantity and quality to minimize prosecuting innocent suspects. They should not wipe up blood before getting samples. They should avoid walking over footprints and fibers that may have been left by the assailant. Also, they should take relevant pictures,
When law enforcement officers do not collect nor examine evidence from a violent crime scene, and when the cleaning of an alleged crime scene prevents any such collection and examination of evidence, a criminal defendant is eligible for a missing evidence jury instruction, including in a recent Maryland appellate case, where a prisoner’s conviction for allegedly stabbing another inmate was reversed for the trial court’s refusal to give such a jury instruction, where prison employees threw away some crime evidence and cleaned the cell of the complainant without first gathering and analyzing evidence. Cost v. Maryland, ___ Md. ___ (Dec. 17, 2010):
Cost was entitled to a jury instruction on the missing evidence because the State had destroyed highly relevant evidence in its custody that it normally would have retained and submitted to forensic examination.