Brady Kiser told cops he realized something was wrong on the evening his son, Trigg, drowned in their backyard pool when he saw his dog acting strangely, according to new documents.

The police released a redacted report about the death of the 3-year-old Friday … and, in it, they say Brady told an officer his son went outside to play after he finished eating.

Cops say Brady told them he was busy with his infant and lost track of Trigg … until he turned to look outside and saw his dog standing over the water.

Officers say they pressed him about certain details that allegedly changed over his retelling of the events … including where he was sitting. They say Brady initially told them he was outside with Trigg, but later admitted he was watching the basketball game inside the house.

However, cops say Brady maintained the game wasn’t his focus … instead, he claims he was trying to feed his infant son.

Emilie wasn’t home at the time … and, cops say Brady told them he let Trigg go out alone. He told police his son would often play outside … but usually with a parent watching.