Warrenton, Ga. ? Autopsies confirmed Tuesday that two toddlers found dead in a sewage pond after disappearing from their home drowned, and the coroner said there appeared to be no sign of foul play.

Jonah Payne, 3, and his 2-year-old sister, Nicole, were reported missing Saturday by their mother, who said they vanished after she went into another room. She said she found the front door open and the children gone.

Their bodies were found Monday in an algae-covered pond a few hundred yards down the road.

Autopsies found no significant injuries to the children’s bodies, said Georgia Bureau of Investigation spokesman John Bankhead. Warren County Coroner Paul Lowe said there appeared to be no foul play.

Authorities continued their investigation, reinterviewing family members and neighbors.

Earlier on the day of the youngsters’ disappearance, Nicole figured out how to unlock the front door and gate and left with Jonah, police said. A neighbor returned the children a half-hour later.