MARTINEZ, Calif., Aug. 13 (San Francisco News Online) — Marcos Eduardo Iriarte-Valdez, 36, has been charged in Contra Costa County Superior Court with murder in the fatal stabbing of Todd Stewart, 68, in Martinez, California. Iriarte-Valdez pleaded not guilty at an Aug. 12 arraignment, according to court reporting and information from the Contra Costa County District Attorney’s Office.
The charge is an accusation. Iriarte-Valdez has not been convicted, and the case must proceed through the court system.
What happened in Martinez?
Stewart was fatally stabbed near his home on Francis Court shortly after 5 p.m. Aug. 6, according to the Martinez Police Department and prosecutors.
Prosecutors allege that Stewart encountered a person during an attempted burglary at or near his residence. The person then fled and stabbed him, prosecutors and police said.
Police arrested Iriarte-Valdez at his home on Aug. 7, according to the Martinez Police Department. The sources reviewed for this report do not include a police probable-cause affidavit or a detailed account of the evidence against him.
The murder case includes an allegation that the killing happened during or immediately after a burglary. Prosecutors also allege that a deadly weapon was used and that the offense occurred while Iriarte-Valdez was released in another case.
Why was his release the focus of the case?
Before Stewart’s death, Iriarte-Valdez was facing cases involving alleged residential burglaries in Orinda on April 29. Court records show he was initially released in those cases in May, according to reports citing the records and Martinez police.
Police said Iriarte-Valdez was taken into custody Aug. 4 for allegedly violating a home-detention monitoring condition. A judge released him on his own recognizance Aug. 5 and referred him back to home detention, according to court records and police information reported about the case.
Stewart was killed the next day.
Martinez Police Chief Andrew White said the monitoring equipment apparently was not placed on Iriarte-Valdez until after Stewart’s death. The exact circumstances of that delay are not established in the available records described in the reports.
At an earlier hearing, Judge David Goldstein described Iriarte-Valdez as a “risk to public safety,” according to court reporting. The available materials do not include the written order explaining the judge’s decision or the full case caption for the earlier burglary proceedings.
What is the status of the murder case?
Iriarte-Valdez was arrested Aug. 7 and entered a not-guilty plea Aug. 12. The Contra Costa County District Attorney’s Office is prosecuting the case.
Reports differ on whether he is being held without bail or whether bail is set at $1.1 million. Because the available accounts conflict and the charging document was not provided, this article does not state a definitive custody or bail status.
The case is expected to return to court for further proceedings, including setting a date for a preliminary hearing. A preliminary hearing is a proceeding in which a judge decides whether prosecutors have presented enough evidence for the case to continue toward trial. The available reports also differ on the date of that next appearance.
What role do federal immigration authorities have?
The Department of Homeland Security said it placed an immigration detainer on Iriarte-Valdez on Sept. 23, 2025. DHS described him as being from Venezuela and as having Spanish citizenship.
An immigration detainer is a request from federal immigration authorities asking a law-enforcement agency to notify them before releasing a person in custody. A detainer does not decide whether a defendant is guilty of a criminal charge.
The available sources establish DHS’s characterization of Iriarte-Valdez’s immigration status, but do not provide independent immigration records confirming it. The criminal case remains a state prosecution in Contra Costa County Superior Court.
What remains unresolved?
The court will still have to address the evidence behind the murder and burglary allegations. The available materials do not include an autopsy report, a formal probable-cause affidavit, the written release order, a defense attorney’s statement or the complete charging document.
Those gaps matter because the current record describes allegations and law-enforcement accounts, not findings by a jury. Iriarte-Valdez remains presumed innocent unless prosecutors prove the charges beyond a reasonable doubt.
