Heather O’Neill pleaded no contest to two child neglect felonies after originally facing an attempted homicide charge.

MERRILL, Wis. — A Wisconsin mother accused in 2023 of intentionally giving her 16-year-old son multiple medications in an overdose received 9 1/2 years of probation after pleading no contest to two amended felony counts of child neglect, ending a case that had once exposed her to a far more severe attempted homicide charge.

Heather Joy O’Neill, 56, entered the pleas July 31 in Lincoln County Circuit Court to neglecting a child resulting in great bodily harm and neglecting a child resulting in emotional damage. Judge Ann Knox-Bauer accepted a joint sentencing recommendation from prosecutors and the defense. The court imposed prison sentences but stayed them while O’Neill serves probation, creating the possibility that she could be sent to prison if her supervision is revoked. The resolution came more than three years after emergency responders were called to O’Neill’s Merrill home and found her teenage son alive but in need of urgent medical care.

On the more serious neglect count, Knox-Bauer imposed and stayed 7 1/2 years of initial confinement followed by five years of extended supervision, while placing O’Neill on probation for 9 1/2 years. On the second count, the court imposed and stayed five years in prison and five years of extended supervision while ordering a concurrent seven-year probation term. A misdemeanor allegation of obstructing an officer was dismissed but read in, allowing the court to consider the underlying conduct when deciding the sentence. O’Neill also received credit for 1,138 days she had already spent in custody.

The case began June 20, 2023, when O’Neill called 911 and reported that she had given herself and her son an overdose, according to the criminal complaint and reports based on court records. O’Neill told authorities that the teenager had been given a mixture of medications that included trazodone, sleep aids and sedatives. Responding officers and medical crews encountered the boy alive, but his condition later worsened at a hospital. He suffered a seizure, stopped breathing and required intubation before ultimately surviving.

Investigators said O’Neill told deputies that she had reached a breaking point after years of what she described as violent behavior by her son, who has autism and was reported to have limited communication skills. At the hospital, she told police she had “snapped” after 16 years of his violent tantrums and said she wanted the situation to be “over for both of us.” Those statements became an important part of the prosecution’s original case but were allegations drawn from police reports and court filings rather than independent findings about the family’s history.

Authorities searching the Merrill home reported finding multiple prescription medication bottles, including containers investigators believed should not yet have been empty, along with other medications. Police also found a note attributed to O’Neill in which she described feeling overwhelmed by her circumstances and wrote bleakly about her relationship with her son. The note and her statements to officers contributed to the initial decision to charge her with attempted first-degree intentional homicide, first-degree recklessly endangering safety and resisting or obstructing an officer.

The attempted homicide charge carried the greatest potential punishment in the original case. When prosecutors filed the case in June 2023, O’Neill was initially held on a $100,000 cash bond. A judge later reduced that amount to $25,000, though local court coverage reported that she remained in custody. At a November 2023 preliminary hearing, a judge found probable cause that a felony had been committed and ordered the case to proceed. The legal path from those allegations to the eventual neglect pleas would take nearly three years.

Questions about O’Neill’s mental condition became a significant part of the pretrial proceedings. In May 2025, she changed her plea to not guilty by reason of mental illness, and the court ordered an examination by the Wisconsin Forensic Unit. The examiner’s report was filed later that year. The defense subsequently sought further review, and the court directed that earlier medical records be considered. The public record described a prolonged evaluation process but did not establish in the reporting reviewed for this article that a court ultimately found O’Neill legally insane at the time of the offense.

The case also encountered delays involving O’Neill’s legal representation. Her first attorney withdrew in late 2024 at her request, and court officials spent months trying to find another lawyer willing to take the case. Attorney John H. Wallace III was appointed in March 2025. In July 2026, court minutes showed that Wallace failed to appear for two consecutive hearings and that court staff and O’Neill had difficulty reaching him. Prosecutors nevertheless reported that they were discussing a possible agreement with the defense, and a negotiated plea was filed July 29.

Two days later, O’Neill entered the no-contest pleas and was sentenced at the same hearing. Her son, who was 16 when the overdose occurred and was by then an adult, attended the proceeding but chose not to address the court, according to court minutes. His presence provided one of the few publicly reported indications of his involvement in the final stage of the case. Authorities had previously reported that he survived the medical emergency, but detailed information about his life or condition after the incident has not been publicly released in the records and reports reviewed.

The conditions of O’Neill’s probation extend beyond ordinary supervision. The court barred her from contacting her son unless he, his legal guardian and his supervising agent all consent. She also may not act in a parental, guardian or supervisory role for a child or an at-risk adult. O’Neill was ordered to undergo a mental health evaluation and complete any treatment recommended as part of that assessment. The court further directed her to write a letter of apology to her son. Court records show that an apology letter was received Aug. 7.

The sentence leaves O’Neill out of prison while preserving substantial incarceration if she fails to comply with probation. The 7 1/2-year initial-confinement term on the principal count was imposed but stayed rather than erased. That distinction means the negotiated resolution did not simply dismiss the possibility of imprisonment; instead, it tied that possibility to O’Neill’s conduct while under supervision. Her more than three years of custody before sentencing were credited by the court, and records showed her address changed from the Lincoln County Jail to a residence in the Merrill area on the day she was sentenced.

The final disposition also sharply changed the legal character of a case that began as an accusation of attempted intentional homicide. Prosecutors ultimately proceeded on child neglect counts tied to the physical and emotional consequences for O’Neill’s son. The court’s acceptance of the joint recommendation resolved the criminal case without a trial on the original attempted homicide allegation, meaning a jury never determined whether prosecutors could have proved that initial charge beyond a reasonable doubt. The plea instead established the amended offenses on which O’Neill was sentenced.

For O’Neill, the case now shifts from prosecution to compliance. Her 9 1/2-year probation term carries the possibility of imprisonment if supervision is revoked, because the court left the imposed prison sentences stayed rather than eliminating them. No additional hearing tied to the 2023 incident was identified in the latest public reporting.

Author note: Last updated November 10, 2026.