Tiraboschi v. State, 312 Ga. 198

In July 2013 Thomas Tiraboschi and cellmate Chris Lowery were housed together at Augusta State Medical Prison; Lowery later was found dead in his cell.
Tiraboschi told two officers he had choked Lowery to death after Lowery said he wanted to die; medical staff also heard him say he killed Lowery while being escorted away.
Autopsy showed petechial hemorrhages, neck muscle hemorrhage consistent with strangulation, lip trauma consistent with forced occlusion of the mouth, and mechanical asphyxia with smothering; the medical examiner ruled the manner homicide.
Tiraboschi did not testify; his defense argued Lowery may have died of natural causes (cardiac event) rather than by strangulation/suffocation.
At trial the court admitted other-act evidence under OCGA § 24-4-404(b) about Tiraboschi’s 1995 vehicular homicide and related convictions for the limited purpose of showing lack of mistake; photos, dashcam video, plea and sentencing documents were admitted; jury was instructed to limit its use.
Jury convicted Tiraboschi of malice murder and felony murder; he received life without parole for malice murder. On appeal his sole claim was that admission of the prior-conviction evidence was erroneous; the Supreme Court held any error harmless and affirmed.

Issue	Tiraboschi's Argument	State's Argument	Held
Whether evidence of Tiraboschi’s prior convictions was admissible under OCGA § 24-4-404(b)	Trial court erred by admitting prejudicial other-act evidence of prior convictions; it was irrelevant and should have been excluded	Evidence admitted only to show lack of mistake; jury was instructed on limited use; alternatively any error was harmless given overwhelming proof	Even assuming error, admission was harmless — highly probable it did not contribute to verdict given confessions, autopsy, limited relevance of other-act evidence, and jury instructions

Jackson v. State, 306 Ga. 69 (2019) (harmless-error standard for nonconstitutional evidentiary errors)
Howell v. State, 307 Ga. 865 (2020) (presumption jurors follow limiting instructions for other-act evidence)
Kirby v. State, 304 Ga. 472 (2018) (greater risk of conviction for extrinsic conduct when extrinsic conduct was not already the subject of a conviction)
Johnson v. State, 301 Ga. 277 (2017) (other-act testimony harmless where substantial evidence of guilt and limited pertinence of testimony)
Rodrigues v. State, 306 Ga. 867 (2019) (admission of prior-conviction evidence harmless where jury already knew defendant was incarcerated and other evidence strongly supported guilt)
Manning v. State, 303 Ga. 723 (2018) (error in admitting prior-conviction evidence harmless in light of other substantial evidence)
Malcolm v. State, 263 Ga. 369 (1993) (merger/vacatur principles regarding felony murder convictions)