People v. Sumagang, H044023M

Background:

Defendant Byron Sumagang was found with the victim Carole Sangco’s body in his lap; police arrested him and later questioned him in a two-part interview: first without Miranda warnings (25 minutes), then after a two‑minute break with full Miranda warnings (45 minutes).
During the prewarning segment Sumagang gave a detailed confession that he choked/strangled Sangco at her request as part of a double‑suicide attempt; much of that content was repeated after warnings when the detective re‑questioned him.
The trial court excluded the prewarning statements (except for impeachment) but admitted the postwarning portion; a jury convicted Sumagang of first‑degree murder and he was sentenced to 25 years to life.
On appeal Sumagang argued the postwarning statements should have been excluded under Missouri v. Seibert (two‑step interrogation) and as involuntary; the People argued Elstad and voluntariness supported admission and that any error was harmless.
The Court of Appeal held the postwarning statements were inadmissible under Seibert (applying Kennedy’s concurrence with Seibert‑plurality factors), found the admission prejudicial, and reversed the conviction; other claims were not reached.

Issues:

Issue	Plaintiff's Argument	Defendant's Argument	Held
Admissibility of postwarning confession under Seibert/Elstad (two‑step interrogation)	Postwarning confession was voluntary, Detective’s failure to warn was a mistake, and Elstad controls so later warned confession was admissible	Detective deliberately or effectively used a two‑step technique; midstream warnings did not cure the taint per Seibert	Reversed — postwarning statements inadmissible under Seibert (applying Kennedy’s intent test informed by Seibert plurality factors)
Whether officer deliberately withheld Miranda (intent to undermine rights)	Officer acted in good faith, did not deliberately withhold warnings	Officer admitted choosing not to warn to “see what he had to say first”; objective factors support inference of deliberateness	Court inferred deliberateness from objective circumstances (continuity, overlap of content, short break, leading questions) and found tactic undermined Miranda
Harmless‑error: did admission of postwarning confession harmless beyond a reasonable doubt?	Other strong evidence (statements at scene, forensic pathology, physical evidence) would sustain conviction	Confession was the most probative evidence; experts and other evidence left reasonable doubt on premeditation without the confession	Not harmless — People failed to show beyond a reasonable doubt that the confession did not contribute to verdict; reversal required
Other claims (involuntariness, intoxication instruction, cumulative error, mental‑health diversion)	N/A (People argued other errors harmless or not preserved)	Raised but trial court rulings rejected or preserved; argued as additional grounds for reversal	Not reached on appeal because reversal based on Seibert error; disposition reversed and judgment vacated

Key Cases Cited

Miranda v. Arizona, 384 U.S. 436 (1966) (custodial‑interrogation warnings required)
Missouri v. Seibert, 542 U.S. 600 (2004) (two‑step interrogation may render postwarning confession inadmissible)
Oregon v. Elstad, 470 U.S. 298 (1985) (postwarning confession may be admissible if made knowingly and voluntarily absent deliberate two‑step tactic)
Arizona v. Fulminante, 499 U.S. 279 (1991) (Chapman harmless‑beyond‑a‑reasonable‑doubt standard for constitutional errors)
Marks v. United States, 430 U.S. 188 (1977) (narrowest‑grounds rule for fractured Supreme Court decisions)
People v. Krebs, 8 Cal.5th 265 (2019) (Cal. Supreme Court application of Seibert/Elstad distinctions)
People v. Camino, 188 Cal.App.4th 1359 (2010) (two‑step interrogation analysis; factual distinctions may uphold postwarning statements)
U.S. v. Williams, 435 F.3d 1148 (9th Cir. 2006) (Seibert factors applied to evaluate effectiveness of midstream warnings)
United States v. Guillen, 995 F.3d 1095 (10th Cir. 2021) (deliberateness may be inferred from objective indicia)
People v. Coffman and Marlow, 34 Cal.4th 1 (2004) (trial court credibility findings given deference)