An autopsy on the boy determined he died of drowning, KATU reported. Pashley said he did not know if Stott-Smith has given a statement to detectives.
Public records show Stott-Smith has charged with a misdemeanor for throwing "lighted objects" and faced excessive speeding tickets and numerous parking violations.
Police are looking for any more details about what happened on the Sellwood Bridge, specifically any sightings of Stott-Smith's a blue Audi sedan near the bridge Friday night.
They would not say, however, how the children wound up in the river.
"We know the bridge is the source where those children came from," said Det. Sgt. Rich Austria with the Portland Police Bureau. "As far as details to the manner of which those children came off the bridge, we're not going to provide that information at this time."
The Associate Press contributed to this report.