Monroe man allegedly killed girlfriend's toddler, injured 5-year-old boy

A 27-year-old Monroe man has been arrested in connection with the death of a 2-year-old girl and injuries to a 5-year-old child, according to the Snohomish County Sheriff’s Office.

The Pacific Northwest Violent Offender Task Force arrested the man at about 7 p.m. Tuesday at a motel on Old Owen Road.

He was booked into the Snohomish County Jail on suspicion of second-degree murder of a child and second-degree assault of a child. He has not been identified by officials pending formal charges.

The case dates back to Dec. 1, 2025, when sheriff’s deputies responded to a home in the 300 block of Avenue J in Snohomish for reports of a 2-year-old female child who was unresponsive.

Fire personnel performed CPR at the scene, and the girl was taken to Providence Regional Medical Center. She was later transported to Seattle Children’s Hospital, where she died Dec. 7, 2025.

Detectives determined the 2-year-old and a 5-year-old child were at home in the sole care of the 27-year-old suspect at the time of the incident, the Sheriff’s Office said.

Investigators said the suspect told them the 2-year-old fell in the bathroom and suffered a head injury, but the injuries were inconsistent with a fall. The Sheriff’s Office also said detectives learned the 5-year-old sustained injuries to his neck and arm caused by the suspect.

Detectives were contacted by hospital staff, who provided information that the child’s injuries were consistent with non-accidental head trauma. The Snohomish County Medical Examiner’s Office determined the 2-year-old’s cause of death was blunt force head trauma and ruled the manner of death a homicide.

Investigators said the suspect is not related to the children and was in a dating relationship with the children’s mother at the time of the incident.

The suspect is expected to make his first court appearance on Wednesday afternoon. The investigation remains active.