State v. Rivas, 34,252

In July 2011, 15-year-old Juan Rivas broke into Clara Alvarez’s home, stabbed and killed her, and took her car; investigators later matched his palm print and recovered a ring he gave to detectives.
On Aug. 1, 2011 (before a delinquency petition), Detective Eubank interviewed Rivas at the police station after reading a juvenile advice-of-rights form; Rivas signed and gave an incriminating statement admitting the killing.
The State filed a delinquency petition on Aug. 2, 2011; at a detention hearing Aug. 3 the court appointed a public defender and a guardian ad litem for Rivas.
On Aug. 6, 2011 (after appointment of counsel and filing), detectives again interviewed Rivas at the juvenile detention center after reading the same juvenile waiver form; Rivas gave a different statement shifting blame to others.
Defense moved to suppress the Aug. 6 statement on the eve of trial (Dec. 6, 2012). The district court denied suppression as untimely and on the merits. Rivas was convicted of first-degree murder and other counts and sentenced to life. The Supreme Court of New Mexico affirmed.

Issue	Plaintiff's Argument (State)	Defendant's Argument (Rivas)	Held
Validity of waiver for Aug. 1 interview (pre-petition)	Waiver was knowing, voluntary, and intelligent; statement admissible	Waiver invalid under Children’s Code and Miranda; counsel ineffective for not moving to suppress	Waiver valid; no prima facie ineffective-assistance claim (affirmed)
Right to counsel for Aug. 6 interview (post-petition)	Rivas knowingly waived again after advisal and signed form	Sixth Amendment attached after filing and appointment; juvenile cannot waive outside counsel/guardian presence	Sixth Amendment right had attached and, for juveniles, is unwaivable outside counsel; district court erred in admitting Aug. 6 statements
Timeliness of suppression motion	Motion was untimely under Rule 5-212; court properly denied on that ground	Timeliness excused; merits should be reached	Motion was untimely, but appellate review reached merits; district court’s timeliness ruling was a valid basis (concurring opinion would dispose on timeliness alone)
Prejudice / Harmless error from admission of Aug. 6 statement	Any error was harmless given the strength of other evidence (including Aug. 1 statement)	Admission of Aug. 6 statement was constitutional error requiring reversal	Error in admitting Aug. 6 statement was harmless beyond a reasonable doubt; convictions affirmed

Miranda v. Arizona, 384 U.S. 436 (U.S. 1966) (requirements for custodial advisals and waiver)
Massiah v. United States, 377 U.S. 201 (U.S. 1964) (post-accusation right to counsel and prohibition on eliciting statements in absence of counsel)
Montejo v. Louisiana, 556 U.S. 778 (U.S. 2009) (Sixth Amendment attachment and waiver discussion in post-accusation questioning contexts)
J.D.B. v. North Carolina, 564 U.S. 261 (U.S. 2011) (children experience custodial interrogation differently; age is relevant to Miranda custody analysis)
State v. Gutierrez, 258 P.3d 1024 (N.M. 2011) (standard of review for suppression rulings and juvenile waiver considerations)
State v. Martinez, 979 P.2d 718 (N.M. 1999) (application of Children’s Code protections to pre-petition juvenile questioning)