An inmate’s death at the Maple Street Correctional Facility on Sept. 29 was the result of toxic effects from fentanyl, the San Mateo County Coroner’s Office determined.
The San Mateo County Sheriff’s Office announced the confirmed cause of 31-year-old Markeisha Monique Renee Blount’s death on Friday. She was the seventh in-custody death in three years, and the fourth officially involving drugs.
Another inmate, 34-year-old Ashley Gromnicki, is alleged to have brought drugs containing fentanyl into the jail and provided them to Blount. Gromnicki was checked in for narcotics and theft charges and was charged with second-degree murder in October. Her case was most recently continued to April 10 to set a preliminary hearing date, District Attorney Steve Wagstaffe said.
The confirmation of death from the Coroner’s Office “verified what we believed about how Blount died,” Wagstaff said. “To that extent, it will allow us to keep going forward and pursuing this case.”
The case against Gromnicki is just the third where the San Mateo County District Attorney’s Office has pursued a homicide charge against the individual who dealt drugs resulting in an overdose, Wagstaffe said. All three were charged in 2025, but Gromnicki’s case was the first involving an in-custody death, he said.
It has only been in the last handful of years that appellate courts have upheld homicide cases against individuals providing drugs recklessly. Previously, individuals were only charged with sale of drugs, but the homicide conviction could result in a life sentence, Wagstaffe said.
Blount was found in her housing unit at the county jail in Redwood City around 6 a.m. Sept. 29 and was pronounced dead after jail staff and paramedics provided aid, including giving her anti-overdose medication.
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Blount’s death was immediately followed by another instance of an individual attempting to enter the jail with drugs. On Sept. 30, 27-year-old Brian Siordia attempted to visit the Maple Street Correctional Facility and was ultimately charged with 11 felony counts after entering the facility eight times prior.
“We know there’s always going to be drugs in incarceration facilities,” Wagstaffe said. “But the goal is to limit it and have the staffing to watch out for that sort of thing.”
Since Jan. 1 2026, the Sheriff’s Office staff has “intercepted drugs on eight separate occasions,” according to a press release by the office.
“The Sheriff’s Office remains dedicated to the highest standards of safety and security in each of its correctional facilities. Deterring and preventing contraband, particularly dangerous drugs, is a top priority for each staff member,” the press release read. “Interceptions underscore the Sheriff’s Office’s zero tolerance stance against contraband and its commitment to safe and secure correctional facilities.”
Wagstaffe said he has had numerous conversations with Sheriff Ken Binder about addressing the safety concerns of incarcerated persons in the jails. Binder was appointed as the San Mateo County Sheriff Nov. 12, 2025.
“Sheriff Bidner is very concerned about this,” Wagstaffe said. “Hopefully that means fewer calls out for us, because there’s fewer deaths. Even if they’re in custody, these are our citizens and we have a duty to protect them.”
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