Detectives built the case through medical findings, surveillance video, witness accounts and an examination of a park’s playground surface.
MULTNOMAH COUNTY, Ore. — The arrest of Dison Ruda in the death of his girlfriend’s 2-year-old daughter followed nearly 15 months of medical analysis, witness interviews and scene reconstruction after the girl was found not breathing at Blue Lake Park.
Ruda, 28, was arrested in Portland on June 10 and charged with second-degree murder, two assault counts and two counts of first-degree criminal mistreatment. He has pleaded not guilty. The case did not begin with a homicide ruling or an immediate arrest. It began as an emergency involving a child whom Ruda said had choked. Investigators later reviewed a separate account about a playground fall, compared both explanations with the girl’s injuries and waited for the Oregon State Medical Examiner’s Office to complete its work.
The investigation’s first day was March 28, 2025. Shortly before noon, deputies were called to Blue Lake Park at 20500 Northeast Marine Drive in Fairview. A nature superintendent had seen Ruda carrying the unresponsive girl. The superintendent said he was blowing into the toddler’s mouth while moving toward a parked vehicle. She urged him to place the child on the ground and then began providing aid herself. Ruda told her the girl had choked on rice, prompting the employee to perform a mouth sweep and the Heimlich maneuver. She found no obstruction.
Deputies reached the park and saw bruises that shifted the focus beyond a possible choking accident. Marks covered the girl’s chest, neck and jaw, according to a probable cause affidavit. Responders said the injuries were too extensive to be explained by the attempted resuscitation they had observed. A deputy also described Ruda as calm and unconcerned. Detectives from the sheriff’s office and the East County Major Crimes Team were brought into the case because the condition of the child suggested that the explanation given at the scene might not be complete.
The next critical stage unfolded at Randall Children’s Hospital. A CT scan showed a large injury on the left side of the brain, pressure that shifted brain structures and widespread swelling. Doctors reported that blood was no longer reaching the brain and that oxygen deprivation had affected the child’s internal organs. The initial medical assessment raised concern about nonaccidental trauma and possible strangulation. The girl died less than 12 hours after arriving. At that point, the investigation involved a child’s death, but authorities still needed to establish the medical cause and manner.
The girl’s mother supplied a timeline for the morning. She said Ruda drove her from the Bybee Lakes Hope Center to a new job and took responsibility for the children while she worked. She told police that the children were not injured when she last saw them. Investigators obtained surveillance video from outside the center. According to KATU’s review of the court documents, the footage corroborated the mother’s account of the family’s departure and helped detectives narrow the period in which the toddler’s injuries could have occurred.
The mother’s statement at the hospital also became part of the affidavit. After seeing the bruises across her daughter’s body, she told officers, “I think he hurt my daughter.” That statement reflected her suspicion at the time; it was not a medical conclusion. Detectives continued gathering independent evidence. They interviewed Ruda with the help of a Chuukese interpreter, spoke with witnesses at the park and collected records from the hospital. The child’s name was withheld in the sheriff’s public announcement to preserve the family’s privacy during the early court proceedings.
During his interview, Ruda described a playground incident that differed from his first statement about rice. He said the child climbed the steps of a slide on all fours and fell from about 6 feet, landing on her forehead in wood chips. He said she did not wake after the fall. Detectives treated the account as a testable claim. They documented the equipment and the ground surface. A detective recorded himself bouncing on the shock-absorbing wood chips, creating a visual record of the material the girl was said to have struck.
Medical specialists then considered whether that type of fall could produce the injuries identified by doctors. The examiner reviewed information about short falls involving young children, the cushioning effect of the wood-chip surface and the distribution of bruises across the toddler’s body. The affidavit said the child had injuries in places not commonly hurt in innocent falls. The examiner also expected to see abrasions if the girl had landed forehead-first in the wood chips, but such abrasions were absent. The resulting opinion was that the brain injury was abusive in origin.
The medical findings addressed more than the claimed fall. The examiner determined that the girl had an acute left subdural hematoma caused by blunt-force trauma to the head. Other reported injuries included bruising to the chin, chest, abdomen, neck, jaw and limbs. The combination of severe brain trauma and marks on multiple areas of the body did not fit either the choking account or the playground explanation, according to investigators. The public record does not say that Ruda admitted striking the child, and prosecutors must prove their allegation through evidence rather than an alleged confession.
On March 16, 2026, the Oregon State Medical Examiner’s Office formally classified the manner of death as homicide. That conclusion came almost one year after the child died. A homicide finding establishes that a death resulted from another person’s act, but it does not identify the legally responsible person or replace a criminal trial. The ruling nevertheless supplied a major element investigators needed before presenting their case to prosecutors. Detectives then worked with the Multnomah County District Attorney’s Office to obtain an arrest warrant authorized by a court.
The arrest occurred about three months after the homicide determination. Deputies and the U.S. Marshals Pacific Northwest Violent Offender Task Force located Ruda at about 6 a.m. near Southeast 92nd Avenue and Southeast Powell Boulevard in Portland. He was booked into the Multnomah County Detention Center. The sheriff’s office announced charges of second-degree murder, first-degree assault, third-degree assault and two counts of first-degree criminal mistreatment. Later reporting based on court records said Ruda entered not-guilty pleas.
Sheriff Nicole Morrisey O’Donnell described the arrest as the product of months of investigative work and a broad partnership. She credited the East County Major Crimes Team, prosecutors, the U.S. Marshals Service, the Oregon State Police Crime Lab, CARES Northwest and clinical staff at Randall Children’s Hospital. Her statement underscored why the investigation extended well beyond the day of the emergency: Detectives relied on specialized medical opinions, forensic review, records and coordination among agencies before asking a judge to approve an arrest.
The timeline is likely to remain important as the case proceeds. Prosecutors will need to connect the child’s injuries to a specific period and to Ruda’s alleged conduct. The defense can challenge the mother’s timeline, the interpretation of video, the medical examiner’s analysis and the weight given to Ruda’s changing explanations. It may also question whether the investigation excluded other possible causes. None of those issues has been resolved by a jury, and the probable cause standard used to support an arrest is lower than the proof required for conviction.
No trial outcome had been reported as of Wednesday. Ruda remains presumed innocent while the charges are pending. The case now rests on evidence assembled over more than a year, beginning with a park employee’s 911 call and ending, for now, with a homicide ruling, a court-approved warrant and a prosecution that must be tested in open court.
Author note: Last updated July 15, 2026.