The $15,000 reward will now be offered to anyone with any information that may lead to the girl's whereabouts.
"From the beginning, statements were always being made that she was deceased or under duress," Kampfer said.
Rumors started Wednesday morning that officials believed Dunn to be dead. Kampfer clarified investigators believe she is likely deceased or under duress.
"Reasonably, she probably is deceased. But I'm adding in an aspect of duress that there may be a slim possibility because I have no proof," he said.
Kampfer said investigators are hoping someone will come forward with information about the girl's whereabouts now that specific clauses regarding the reward have been removed.
"We're eliminating things like 'successful prosecution'. The additional one is a safe return of Hailey. Although we would very much like the safe return of Hailey, that may not be likely," he said.
Kampfer said law enforcement may increase the reward up to six figures if no one comes forward.
Hailey was last seen on December 27. Her mother's boyfriend, Shawn Adkins, remains the only named suspect.
"I'm hoping that we don't have a six month or a year type of request to her status or her location. We're trying as best we can and we have a lot of resources available to locate Hailey," Kampfer said.
Colorado Middle School principal Mark Merrell came to speak with Kampfer late Wednesday morning to squash a rumor that investigators had found Dunn's body circulated around the school.