A Umatilla father has been sentenced to 15 years in prison followed by 10 years of probation for his role in the 2021 fentanyl overdose death of his 2-year-old daughter.
Joseph Arthur Tierney, 40, received the sentence following his plea of “nolo contendere” to aggravated manslaughter of his late child. According to court records, Tierney was credited with 4 years, 4 months, and 20 days of time already served in the Marion County Jail.
The case dates back to June 13, 2021, when Marion County Sheriff’s Office deputies and paramedics responded to a residence on SE Highway 42 in Umatilla in reference to a 911 call regarding an unresponsive toddler.
Despite administering CPR at the scene and transporting the child, later identified as Miya Tierney, to The Villages Hospital, she was pronounced deceased at 9:30 p.m.
Initial interviews with the child’s parents, including her 38-year-old mother Jalynn Nichole Davis, provided a timeline of the evening.
Tierney originally told deputies that he had been napping with Miya when Davis entered the room. The couple admitted to leaving the child alone in the bedroom for approximately 30 minutes while they had sexual intercourse in another room. They claimed that upon returning, they found the child unresponsive with vomit coming from her nose and mouth.
In August 2021, autopsy and toxicology results from the Medical Examiner’s Office confirmed the child died of “Fentanyl Toxicity.” High levels of the potent narcotic were found in her blood, urine, and vitreous fluid. Most notably, detectives discovered fentanyl within the child’s stomach contents, suggesting the drug had been ingested.
During their investigation, MCSO detectives learned that the residence where the child died was a known drug location. While Tierney claimed he had “thoroughly cleaned” the house before the child arrived, he later admitted to being an active user who struggled with a 20-year addiction.
During a post-Miranda interview, Tierney admitted to injecting “downers” and “blues” (street names for fentanyl and oxycodone). He confessed to having a half-gram of fentanyl on the night of his daughter’s death and admitted to using “two tenths of a gram” just before the child arrived at the home.
The child’s mother, Jalynn Davis, was also identified as a suspect in a separate Lake County homicide involving a drug overdose. During a search warrant executed at Davis’ residence in July 2021, authorities recovered a massive cache of narcotics, including fentanyl, crystal methamphetamine, powdered codeine, and oxycodone.
In the arrest affidavit, Major Crimes detectives noted that while Tierney claimed to be a “responsible” user who kept his drug stash locked in a bathroom drawer, he failed in his role as a caregiver to protect the child from a lethal environment. Detectives concluded that Tierney’s admitted drug use and his decision to bring a toddler into a known drug house constituted culpable negligence.
At the time of his formal charging in the manslaughter case, Tierney was already being held for aggravated assault and tampering with a witness.
In a letter written to his judge in late 2024, Tierney indicated that there were two videos that would exonerate him and clear his name. At the time, Tierney alleged that his attorney was ignoring his requests and that she was negligent in her handling of his case.
Davis is still defending her case in the legal system for her alleged role in the death, as well as separate murder charges in Lake County related to the unlawful distribution of fentanyl.
As part of his 10-year probation, Tierney is required to perform 200 hours of community service. If he resides in Marion County, those hours must be completed through the Marion County Solid Waste litter control program within 24 months. Should he move to a different county, the service may be completed at any location approved by the court.