As searchers continued Wednesday to explore the backcountry of Joshua Tree National Park for a missing California hiker, they found tracks believed to be his that headed off trail into a rugged area of the Little San Bernadino Mountains.

Edward Rosenthal, of Culver City, failed to return from a hike near the Black Rock Campground last Friday, although park officials weren't notified of his disappearance until Sunday.

The footprints found Wednesday were in an area south of the original search area, according to a park release. Trackers followed them off trail, but as of 5 p.m. Pacific Daylight Time Wednesday no other sign had been observed.

A San Bernardino County Sheriff’s Office helicopter and ground search teams combed a region several miles south of the original search area finding additional tracks but without finding the missing hiker. For the first time, ground teams were directed to search from the park’s south boundary north into the search area, park officials said.

Incident commanders planned a full day of search activity for Thursday with intentions to concentrate on the area where Mr. Rosenthal’s tracks appeared to be leading. The search area is now focused on an area of deeply cut canyons, ravines, and rocky ridges between Black Rock Canyon and Desert Hot Springs.