The Contra Costa County District Attorney has charged 36-year-old Marcos Eduardo Iriarte-Valdez with murder after prosecutors say he fatally stabbed 68-year-old Todd Stewart outside his Martinez home during a burglary on Aug. 6. Iriarte-Valdez had been released on his own recognizance and placed on home detention monitoring a day earlier in an unrelated burglary case. He was arrested the day after the killing after police traced a Cadillac SUV to his location; he pleaded not guilty and is being held without bail. ICE has lodged a detainer, and prosecutors say he faces additional charges and could face life without parole if convicted.
Released From Custody Day Earlier, Man Charged With Murder After Fatal Martinez Stabbing
Man accused of fatal stabbing day after his release from jail charged with murder
A 36-year-old man has been charged with murder after prosecutors say he fatally stabbed a 68-year-old man outside his Martinez, California, home during a residential burglary on Aug. 6.
Authorities identified the suspect as Marcos Eduardo Iriarte-Valdez, who was reportedly on electronic monitoring in a separate burglary case at the time of the killing, according to the Contra Costa County District Attorney's Office. Surveillance footage captured the assault, and the victim, Todd Stewart, was pronounced dead at the scene, Martinez police said.
Incident and Arrest
Prosecutors say the assailant fled the scene in a Cadillac SUV. Investigators traced the vehicle by its license plate and located it in Martinez the next day; Iriarte-Valdez was arrested following that discovery. Police allege he stabbed Stewart with a knife while committing the burglary.
Pretrial Status and Timeline
Records show Iriarte-Valdez had been taken into custody on Aug. 4 for allegedly violating the terms of home detention while awaiting trial on residential burglary charges related to April incidents in Orinda. On Aug. 5 he was released on his own recognizance and placed on home detention monitoring; the fatal stabbing occurred on Aug. 6.
Martinez Police Department - PHOTO: A suspect in a deadly stabbing in Martinez, California, on Aug. 6, 2026, is seen in a surveillance video still released by police.
Charges and Court Proceedings
The Contra Costa County District Attorney's Office filed one count of murder with enhancements alleging the killing occurred during a burglary, involved a knife, and was committed while the defendant was on conditional release in an unrelated case. At arraignment, Iriarte-Valdez pleaded not guilty and a judge ordered him held without bail, citing him as a 'risk to public safety,' according to prosecutors.
'Our office will pursue this case with diligence and integrity to hold Iriarte-Valdez fully accountable under the law for this devastating act of violence,' District Attorney Diana Becton said. 'Our thoughts are with the victim's loved ones and the larger community as they navigate this unimaginable loss.'
Additional Information
Immigration and Customs Enforcement lodged a detainer with the county jail on Aug. 8. A Department of Homeland Security spokesperson described Iriarte-Valdez as a Venezuelan national who also holds Spanish citizenship and was legally admitted to the U.S. in December 2007. The DHS spokesperson also said he faces other alleged offenses, including burglary, trespassing and inflicting corporal injury on a spouse, and has a prior conviction for violating a protective order.
A memorial fund for Stewart described him as 'a very loving, kind and helpful person' who was devoted to his family and church. He was a recently retired engineer and is survived by his wife and two children.
If convicted of murder, Iriarte-Valdez faces a possible sentence of life in prison without the possibility of parole.
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