O'Connell was abducted as she walked home from a Sioux Falls neighborhood convenience store on the evening of May 8, 1990, by Donald Eugene Moeller (August 5, 1952 – October 30, 2012), a 38-year-old man with a history of attempted sexual assaults who lived in the area.
Moeller took O'Connell to a wooded area along the banks of the Big Sioux River east of Lake Alvin in Lincoln County.
He remained on South Dakota's death row for over twenty years until he was executed by lethal injection on October 30, 2012.
He maintained his innocence throughout his time on death row before eventually confessing to the crime in the final months leading up to his execution.
[2] On the evening of May 8, 1990, nine-year-old Becky O'Connell disappeared from a Sioux Falls neighborhood convenience store where she had gone to buy candy and sugar to make lemonade at home.
[3][4] The following morning, O'Connell's naked body was found in a wooded area along the banks of the Big Sioux River near Lake Alvin in Lincoln County.
One lead caught the eye of Detective Mike Larsen, who noticed a man named Donald Moeller, who had a long criminal history, lived near the area where O'Connell had been abducted from.
Additionally, heavy rains had occurred on the night of O'Connell's death and the crime scene had been covered in mud and dirt as a result.
A routine FBI check of Moeller's fingerprints taken by the Tacoma Police Department revealed he was wanted in South Dakota on an assault charge unconnected with O'Connell's murder.
[1] In July 2012, a South Dakota circuit court judge set the execution window for Moeller to occur between October 28, 2012, and November 3, 2012.
A federal judge dismissed a pending suit challenging South Dakota's execution protocol after Moeller said he did not want to be a part of it.
[1] On October 30, 2012, Moeller was executed by lethal injection at the South Dakota State Penitentiary in Sioux Falls.
It was later revealed by the South Dakota Department of Corrections that several witnesses had reported hearing voices or audible noises as well as sounds of cheering as Moeller made his last statement.
Department of Corrections staff members later reported that they could distinguish the voices and sounds of cheering coming from other inmates in a nearby housing unit.