Jail staff told a woman with Lussier that he could turn himself into Iron County instead. A sergeant then said they could book him in Vilas County and asked him to have a seat. That's when Lussier, 19, and the woman left the jail, Fath said.
Staff did not identify Lussier, confirm if he had warrants, notify dispatch or notify patrol, Fath said.
Lussier was arrested nine days later in Oshkosh. Four others suspected in the slaying were arrested earlier.
Fath said after an investigation into the staff failures, including a decision to cover up the mistakes, a corrections sergeant and a corrections officer were placed on leave and both have resigned. Another corrections officer has been suspended without pay and demoted.
Two other officers could face punishment as well, the sheriff said.
No names were released.
"All jail staff have been instructed on the facts of this incident," Fath said in a statement. "Review of corrections officers duties and jail policy concerning receiving inmates at the jail have been completed."
Jail staff are civilians without power to make arrests, the sheriff said.