On Friday, the Hughes County Sheriff's Office reported it completed the investigation into two bodies recovered on Wednesday night at Farm Island.
The Sheriff's Office said a forensic examination indicated 60-year-old Pierre resident Charles Serbousek likely died of a heart attack before his body entered the water. Crews also recovered 6-year-old Joseph Serbousek from the water. The Sheriff's statement reported his death as drowning.
The Sheriff's Office stated it released the names with the family's permission. Sheriff Callahan asked the family's privacy be respected.
The Sheriff's Office responded to Farm Island on Wednesday after receiving two missing person reports shortly after 11 p.m.
The Sheriff's Office said deputies and State Game, Fish and Parks officers searched the area after receiving the reports that Charles and Joseph were last seen fishing.
Crews recovered the two from the water shortly after aerial UAVs from Hughes County Emergency Management and divers from the Pierre Fire Rescue Squad joined the search.