Anne Cameron was last seen near an aged care facility in Port Douglas on Tuesday afternoon and her family believe she passed away in "tragic circumstances".
'We believe she's wandered in there and gotten lost, it's our theory that she's become disorientated and walked through that area'.
A major search has been underway since yesterday with the clothing items located at the isolated creek today.
Isabella Eggins, a granddaughter of Ms Cameron, said the family feared the 79-year-old had died in tragic circumstances.
"We've also located some biological matter which we believe to be human remains, but those items are now being tested in Cairns", acting inspector Ed Lukin said, according to ABC.
"Because of the proximity of these items and this unknown material located by this creek bank we can not rule out a croc attack", Acting Insp Lukin said.
"We also located a walking stick with her name on it, we have also located some biological matter which we believe to be human remains".
The forensic tests should be completed by Friday morning, and police and SES are continuing to search for the missing woman.
"We still hold our hope that we will find this missing person alive, of course as the days progress that option will diminish, and as time goes by we will continue to reassess our searching options".
The woman was reported missing from the OzCare aged facility.
Crocodiles in the region are territorial and known to be extremely aggressive.
Lee de Paauw, 18, injured after he was dared to jump into an Innisfail river in the middle of the night.
She had moved to the nursing home recently to be closer to relatives, local media said.
A 47-year-old man was killed by a crocodile after wading into a river crossing near Kakadu National Park in the Northern Territory. His mate was trapped for three hours and was rescued after throwing spanners and spark plugs at the croc.
Anne Cameron went missing Tuesday in Port Douglas, Australia.