Department of Environment wildlife officers last night located the crocs, measuring 4.1 metres and 2.8 metres, upstream from where Kevin Darmody was last seen.
His friend alerted police and described hearing a “splashing sound” just before Darmody disappeared.
A police statement said the crocodiles are “believed to be involved in the incident”.
The search for Darmody, a 65-year-old publican and fishing enthusiast, today entered its fourth day, with chances of his survival dwindling fast.
Police dive teams have been working in the extremely dangerous waterways, and other search and rescue teams are combing the area.
Speaking to reporters yesterday, Detective Acting Inspector Jason Chetham said it was “obviously” possible that Darmody was dragged into the water by a big croc.
“It could have happened, for sure,” he said.
“It’s a national park and there are wild animals up there, wild crocodiles,” he said.
Darmody was last seen at 3.30pm on Saturday at the Kennedy River at Rinyirru (Lakefield) National Park, about 340km north-west of Cairns.
Queensland police will update search progress this afternoon.