Anne Cameron, 79, who police said might have dementia, was last seen on Tuesday at a care home near the tourist town of Port Douglas on Australia's northeastern coast.
Queensland Police and the State Emergency Service were searching for her when they came across clothing and a walking stick with her name on it.
"We've also located some biological matter which we believe to be human remains," Queensland Police Acting Inspector Ed Lukin told reporters.
But he said that as the items were "located near (a) creek bank, we cannot rule out the possibility of a croc attack".
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Lukin said police believed Cameron had wandered into the dense bushland, where she became lost, but it was not known if she had entered the water.
"She may suffer from dementia and her clothes may have been removed voluntarily," he added.
A 2.6-metre long saltwater crocodile was caught at Dickson Inlet near Four Mile Beach in Port Douglas in August, according to the Australian Broadcasting Corporation.
Saltwater crocodile numbers have exploded since they were declared a protected species in the 1970s, with recent attacks reigniting debate about controlling them.
The "salties", which can grow up to seven metres long and weigh more than a tonne, are a common feature of the vast continent's tropical north and kill an average of two people a year.