A Merrill, Wisconsin, woman once accused of trying to kill her teenage son has avoided prison for now after pleading no contest to two felony counts of child neglect.
Heather Joy O’Neill, 56, entered the pleas on July 31 in Lincoln County Circuit Court, bringing a more than three-year-old criminal case to a close. The original charges included attempted first-degree intentional homicide and first-degree recklessly endangering safety.
The case began on June 20, 2023, when O’Neill called 911 from her Merrill home and reported that she had given medication to herself and her 16-year-old son. The boy, who has autism, was later hospitalized after suffering a seizure and experiencing serious medical complications. He required intubation while receiving treatment.
Investigators said O’Neill told authorities that she had given her son several medications, including prescription drugs and sleeping aids. During the investigation, officers also found prescription medication bottles at the home and a note written by O’Neill. She told investigators that she had reached a breaking point after years of difficult behavior involving her son.
The teenager survived the incident and was present in court when his mother was sentenced on July 31. He chose not to address the court.
Under the plea agreement, O’Neill was sentenced to 9½ years of probation. The court also imposed a 7½-year prison sentence on the more serious child-neglect count but stayed that sentence, meaning she will not serve it unless she violates the conditions of probation. A separate seven-year probation term on the second count will run at the same time.
The conditions include restrictions on contact with her son. O’Neill cannot have contact with him unless he, his legal guardian and the guardian’s agent all agree. She is also prohibited from taking on a parental, guardian or supervisory role for a child or an at-risk adult.
The court additionally ordered O’Neill to undergo a mental health evaluation and follow any recommended treatment. She was required to write an apology letter to her son, and court records show that the letter was filed on Aug. 7.
O’Neill was given credit for 1,138 days already spent in custody, covering more than three years. Her address was also changed from the Lincoln County Jail to a Merrill-area residence following the sentencing.
The case had been delayed for an extended period while questions surrounding O’Neill’s mental health were addressed in court. In 2025, she entered a plea of not guilty by reason of mental illness and underwent a forensic evaluation. Her defense later sought another evaluation and the court directed the original examiner to review additional medical records.
There were also changes in legal representation during the case. Her first attorney withdrew in late 2024, and months passed before another lawyer was appointed. A negotiated plea agreement was ultimately filed in late July, shortly before O’Neill entered her no-contest pleas.
The resolution means O’Neill will remain under court supervision for the next several years rather than immediately entering prison. If she violates the terms of probation, the stayed prison sentence could be activated.
