ST. LOUIS – A woman will be sentenced Friday for the 2018 murders of Malcolm Mathis and his 2-year-old son.

Onyai Turner pleaded guilty to two counts of second-degree murder, first-degree robbery, and three counts of armed criminal action.

Malcolm Mathis II, 33, and 22-month-old Malcolm Mathis III were found stabbed to death at a home in the 12400 block of Marine Avenue in Maryland Heights on the evening of Feb. 15, 2018. The slain father’s 4-year-old daughter and mother-in-law were badly injured during the gruesome attack but survived.

“The stabbing deaths of Mr. Mathis and his toddler son were among the most despicable and gruesome murders ever committed in St. Louis County,” St. Louis County Prosecuting Attorney Wesley Bell said.

Turner’s boyfriend, Traveon Sims, is Mathis’ nephew. Sims is already serving life in prison for the crimes. He pleaded guilty in 2021. Sims admitted to stabbing the children and the mother-in-law and then waited for Malcolm Mathis II to arrive home before attacking him. Turner waited outside while the murders occurred and entered the home a short time later. She was charged as an accomplice.