After two-and-a-half weeks of intense searching through heavy brush, there's still no sign of 20-year-old Christina Calayca, who vanished while camping with three others at Rainbow Falls Provincial Park near Thunder Bay.

The lack of progress has weighed heavily on her family. 

"They've used K-9 units. They've used planes. They've used submarines. They've used all sorts of different ways in order to find Christina. And nothing, absolutely nothing works. There's no clue at all," said her distraught uncle Ken West.

The O.P.P. are changing their search tactics and no longer looking for Christina by airplane or helicopter. Instead searchers on the ground will be working closer together, moving in a grid-like fashion, looking specifically for someone who may not be able to respond.

"She could be unable to communicate with us. She could be injured, unconscious, or she could have passed away," said Sgt. Deb Tully.

Christina's mother is part of the search team, and she hasn't given up hope.

"I won't live without finding my daughter," she said.  "I want to see her...I know from the bottom of my heart as a mother, she is alive. She is just kept by somebody. I want to find out who," she adds, referring to a possible kidnapper.