We do that–right. Make an issue of the MCIO failures to investigate, their tunnel vision, their confirmation bias, and overall bias.
Here’s an Article that might help.
Lisa Steele, Investigating and Presenting an Investigative Omission Defense. 57 CRIM. L. BULL. (2021) (Forthcoming).
“This paper explores defense challenges to the adequacy of police investigations, and investigative lapses as a cause for reasonable doubt. It focuses on case law from Massachusetts, which has four decades of state appellate case law about investigative omission evidence and jury instructions. It talks about the constitutional nature of the defense, how it differs from third-party culprit defenses, and evidence issues that may arise.
The paper also discusses cognitive biases that can affect even well-trained, experienced police investigators and/or prosecutors. Tunnel vision, confirmation bias, and other mental shortcuts can lead to investigative lapses when evidence that the defendant is not the culprit is mentally ignored or downplayed.”
And, the abstract,
When the [investigators’] failure to gather evidence is merely negligent, an oversight, or done in good faith, sanctions are inappropriate, but the defendant can still examine the prosecution’s witnesses about the deficiencies of the investigation and argue the investigation shortcomings against the standard of reasonable doubt. The State is, after all, still charged with proving its case beyond a reasonable doubt, and in many cases, the failure to gather physical evidence at the crime scene impairs the State’s ability to prove its case. We believe that this test strikes a fair balance between safeguarding the defendant’s right to a fair trial while taking into account society’s interest in having effective law enforcement, obtaining convictions for guilty defendants, and in insuring that the truth in criminal proceedings is revealed.