We turn to the search for that missing California firefighter who left his campsite a week ago chasing after his dog but never came back. They're using drones to look for him and may have discovered... See More
We turn to the search for that missing California firefighter who left his campsite a week ago chasing after his dog but never came back. They're using drones to look for him and may have discovered an important clue. David Wright has the story. Reporter: It's one week to the day since Mike herdman vanished in this vast wilderness area. Now rescuers are turning to a high-tech tool to help the search. Drones armed with infrared camera, the hand launched puma -- They're a force multiplier. Instead of 30 guys in the field looks, we can launch this aircraft and cover a lot of ground. Reporter: His friend told authorities he last saw him Friday chasing after his dog wearing only a t-shirt and shorts. Get you out safely. Reporter: Search crews from half a dozen agencies including this homeland security rapid response team have been scouring the back country. A wilderness area twice the size of the grand canyon. Every footprint is a clue. Every broken branch. That's what we're looking for. Reporter: Wednesday and Thursday they spotted the dog duke but duke got away. So they're taking along a decidedly low-tech tool. We're going to be given harmonicas. ? Reporter: Hoping the music will put duke at ease. Herdman's family and friends are convinced his fitness and training have kept him alive. I have no doubt that he can survive out there for weeks. He's just an amazing person. Very, very resourceful. Reporter: They're all gathered at the trail head hoping he'll come over the ridge. I think everybody on the hill would just be elated and overjoyed. Reporter: For "Good morning America," David Wright, ABC news, Los Angeles. Still. We have our fingers crossed here that they will certainly find something to figure out what happened to him. Still holding out hope.
This transcript has been automatically generated and may not be 100% accurate.