He Was Released Wednesday Without His Ankle Monitor. The Next Day, a Retiree Was Dead in His Own Front Yard.
- Aug. 6, 2026 the day Marcos Iriarte-Valdez, 36, allegedly stabbed Todd Stewart, 68, to death in Stewart's own front yard on Francis Court in Martinez while the retired engineer was building a shed — New York Post; KTVU, Aug. 11, 2026
- Under 24 Hours how long after his release on his own recognizance Iriarte-Valdez allegedly killed Stewart — while the ankle monitor his release order required sat off — KTVU, Aug. 11, 2026
- 2 Burglary Charges the pending residential burglary counts Iriarte-Valdez already faced, including an April 29 Orinda break-in where police say he ate an 83-year-old woman's food while she was home — KTVU, Aug. 11, 2026
- 3 Days how long Iriarte-Valdez went without a working ankle monitor — removed when he was taken into custody Tuesday, not replaced until Friday, the day after the killing — KTVU; RedState, Aug. 11, 2026
- Special-Circumstance Murder the charge Contra Costa County DA Diana Becton (D) filed Aug. 11 — murder allegedly committed during flight from an attempted burglary — RedState; New York Post, Aug. 11, 2026
Todd Stewart, 68, was building a shed in the front yard of his own home on Francis Court in Martinez, California, on the afternoon of August 6, 2026, when a gray Cadillac SUV pulled up outside, according to police and surveillance footage from the scene. A man got out, pulled on a mask and a tactical vest, and — armed with a large knife — attacked Stewart in his own yard. Police say the retired engineer was stabbed to death in the assault.
The Department of Homeland Security identified the attacker as Marcos Iriarte-Valdez, 36, a Venezuelan national living in the country illegally. Investigators tracked the Cadillac using license-plate-reader technology and arrested Iriarte-Valdez the next day, August 7, according to police.
What made the killing possible, according to court records reviewed by Bay Area outlets, was not a gap in surveillance technology. It was a gap in supervision. Iriarte-Valdez was already free on pretrial release for two pending residential burglary charges when a Contra Costa County Superior Court judge released him again — less than 24 hours before Stewart was killed — with no working ankle monitor on his leg.
Court records tied to Iriarte-Valdez’s case start months earlier, in Orinda, about ten miles from Martinez. On April 29, 2026, police say he broke into the garage of an 83-year-old woman’s home — and, while she was inside, helped himself to food from her kitchen before leaving. He was charged with residential burglary. A second residential burglary charge, also out of Contra Costa County, followed.
Rather than hold Iriarte-Valdez in custody through trial, the court released him on pretrial supervision, with electronic home detention as a condition — an ankle monitor tracking his location around the clock, standard practice for defendants a judge has decided don’t need to sit in jail while their cases move through the system.
That kind of release is a routine tool, not an anomaly — courts across the country use electronic monitoring to manage jail crowding and let defendants keep jobs and housing while a case is pending. The system depends on two things working together: a defendant who complies, and a monitor that is actually on when the court believes it is. Iriarte-Valdez’s case shows what happens when the first assumption fails and the second one goes unverified at the exact moment it matters most.
The supervision didn’t hold. On Tuesday, August 4, 2026, Iriarte-Valdez was arrested again — this time for violating the terms of his home-detention release, according to KTVU. Taken back into custody, he had his ankle monitor removed.
The next day, Wednesday, August 5, Contra Costa County Superior Court Judge Nichelle N. Holmes — appointed to the bench by Gov. Gavin Newsom (D) in March 2024 — released Iriarte-Valdez on his own recognizance, ordering him back onto electronic home detention as a condition of release. But according to KTVU’s reporting on the timeline, no monitor was placed back on him before he walked out of custody.
He was not monitored again until Friday, August 7 — the day after Todd Stewart was killed, and the same day Iriarte-Valdez himself was arrested for the killing. In between, less than 24 hours after Judge Holmes signed his release, Iriarte-Valdez allegedly drove a gray Cadillac SUV to Francis Court and stabbed Stewart to death in Stewart’s own front yard.
“He was released not once, but twice. Then he went out and randomly murdered somebody.”
RedState headline, Aug. 11, 2026
Contra Costa County District Attorney Diana Becton (D) — unanimously endorsed by the county’s Democratic Party in her most recent election — filed the charge against Iriarte-Valdez on August 11: murder with a special circumstance, alleging the killing occurred during his flight from an attempted burglary. Special-circumstance murder carries the county’s most serious penalty exposure short of the death penalty, which California does not currently carry out.
Combined with the two outstanding burglary counts from Orinda, Iriarte-Valdez is now facing the full weight of a criminal justice system that, twice in the space of four months, had already decided he could be supervised in the community rather than held. He is currently in custody without bail.
DHS’s identification of Iriarte-Valdez as a Venezuelan national living in the country illegally immediately raised the obvious question: did federal immigration authorities ever ask Contra Costa County to hold him, and did the county say no? As of publication, no reporting reviewed for this story identifies a specific ICE detainer that the Contra Costa County jail declined to honor in Iriarte-Valdez’s case — and it would be inaccurate to claim one was rebuffed.
What is documented is the legal backdrop. California’s statewide TRUST Act sharply limits when local jails may notify or cooperate with ICE at all, regardless of what any individual county chooses to do beyond it. Contra Costa County itself has not adopted the kind of formal ICE non-cooperation ordinance that neighboring Alameda, San Francisco, and Santa Clara counties have — though county supervisors, including Shanelle Scales-Preston (D), whose district covers Martinez, have discussed adding one. Contra Costa County Sheriff David O. Livingston runs the jail Iriarte-Valdez cycled through twice in four months; Martinez Police Chief Andrew White’s department led the manhunt and the arrest.
The distinction matters for accountability, not just semantics. A confirmed rebuffed detainer is a specific decision by a specific official to let a specific person go. What happened here is broader and, in some ways, harder to fix with a single policy reversal: a state law that keeps local jails largely out of the business of immigration enforcement by default, layered on top of a county court system that twice decided Iriarte-Valdez didn’t need to be held pending trial. Both decisions were legal. Neither was reviewed against the other before Stewart was killed.
Iriarte-Valdez was arraigned on the special-circumstance murder charge August 13, 2026 — seven days after Stewart’s death. He pleaded not guilty through counsel. Prosecutors sought and won a bail denial, citing the special-circumstance allegation and the exposure to life without parole it carries; Iriarte-Valdez also waived his right to a speedy preliminary hearing. His next court date is September 1, 2026. He is presumed innocent unless and until a jury finds otherwise, and the case, including any additional charges tied to the Orinda burglaries, is still in its earliest stages.
What is not in dispute is the timeline that put him on Francis Court unsupervised: two pending burglary charges, a violation arrest, an own-recognizance release from Judge Holmes’s courtroom, and a missing ankle monitor — all inside the same 48 hours that ended with Todd Stewart dead in his own front yard, building a shed.
On August 6, 2026, Marcos Iriarte-Valdez, 36 — a Venezuelan national living in the country illegally, according to DHS — allegedly stabbed Todd Stewart, 68, to death in Stewart’s own front yard in Martinez, California. Iriarte-Valdez was on pretrial release for two residential burglary charges at the time, and had been released from custody by Contra Costa County Superior Court Judge Nichelle N. Holmes — a Gov. Gavin Newsom (D) appointee — less than 24 hours before the killing, without a working ankle monitor. Contra Costa County DA Diana Becton (D) charged him August 11 with special-circumstance murder; he pleaded not guilty at his August 13 arraignment, bail was denied, and his next court date is September 1, 2026. No ICE detainer has been confirmed rebuffed in this specific case — the documented failure here is a supervision gap inside the local court system, not a specific immigration-enforcement request that was ignored.
