State v. Lopez, 417 P.3d 116

Shannon Lopez was found shot in the head in a pickup truck after an argument with her husband, Komasquin Lopez; physical evidence (wound location, gun placement, GSR, blood spatter) was inconclusive about who fired.
Shannon had prior statements and behavior suggesting suicidal ideation; she had toxic levels of methamphetamine at death. Lopez also had methamphetamine in his system.
The State’s theory: Shannon did not commit suicide; Lopez did. Defense theory: Shannon shot herself.
The State introduced Dr. Craig Bryan, a clinical psychologist, who applied the Fluid Vulnerability Theory of Suicide (FVTS) to opine that Shannon’s behavior was inconsistent with suicide. The defense introduced an expert who called the death a “classic suicide.”
The State also introduced two prior-act 404(b) incidents: (1) Lopez allegedly pointed a gun at Shannon’s left ear during a demonstration about killing; (2) Lopez allegedly pointed a gun at an ex-wife and threatened to kill her if she left. Four other proffered incidents were excluded.
The jury convicted Lopez of murder and use of a dangerous weapon; the Utah Supreme Court reviewed admission of the expert testimony and the 404(b) evidence and reversed.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Admissibility and reliability of expert testimony applying FVTS to a decedent	FVTS is generally accepted in the psychological community and reliably assesses suicide risk	FVTS was not shown to be reliable when applied post-mortem; State failed to lay foundation	Court: Abuse of discretion to admit Dr. Bryan’s FVTS opinion because the State did not show FVTS is reliable for assessing suicide risk of someone who is deceased; error was harmful
Admission of prior-act evidence (404(b)) to prove identity	Prior acts showing Lopez pointing guns at family members were relevant to identity of the shooter (non-character purpose)	The prior-act evidence was impermissible propensity evidence and lacked sufficient similarity/foundation for modus operandi or doctrine of chances	Court: Abuse of discretion to admit the two prior acts; they did not show a unique modus operandi nor satisfy doctrine-of-chances foundations; error was harmful
Cumulative error / sufficiency of evidence	(State) Errors were harmless given other evidence	(Lopez) Errors were harmful and undermined verdict; also argued insufficiency	Court: Did not reach cumulative/sufficiency because reversal was required on above errors

State v. Maestas, 299 P.3d 892 (Utah 2012) (standard of review and district court gatekeeping for expert testimony)
State v. Thornton, 391 P.3d 1016 (Utah 2017) (evidentiary standards and rule 404(b) context)
State v. Lucero, 328 P.3d 841 (Utah 2014) (prior-act evidence as modus operandi and high similarity requirement)
State v. Reece, 349 P.3d 712 (Utah 2015) (prior acts used to show access to murder weapon as intermediate inference for identity)
State v. Verde, 296 P.3d 673 (Utah 2012) (doctrine of chances foundational requirements: materiality, similarity, independence, frequency)
State v. Lowther, 398 P.3d 1032 (Utah 2017) (discussion of doctrine of chances in non-character contexts)
State v. Hamilton, 827 P.2d 232 (Utah 1992) (harmlessness analysis for improperly admitted character evidence)
State v. Webster, 32 P.3d 976 (Utah Ct. App. 2001) (reversal where improperly admitted character evidence could have been decisive)
State v. Decorso, 993 P.2d 837 (Utah 1999) (prior crimes admitted as signature-like modus operandi)
State v. Clark, 322 P.3d 761 (Utah Ct. App. 2014) (prior shooting showed access/familiarity with same firearm to support identity)