KADENA AIR BASE, Okinawa — A professional search-and-rescue team from Moffett Field, Calif., discovered footprints they believe belong to an American hiker missing since April 27 on a Japanese island.

The four-person team from the nonprofit 1st Special Response Group responded to the area at the request of the family and friends of Craig Arnold, 41, a renowned poet and assistant professor at the University of Wyoming. He has been missing since he went on a solo trek up volcanic Mount Shindake on tiny Kuchinoerabu Island, some 30 miles south of Kyushu.

Japanese police called off their official search for Arnold on Tuesday after a large party of police and local residents found few clues of his whereabouts. Their search was assisted last Thursday and Friday by four helicopters assigned to the 33rd Rescue Squadron based at Kadena Air Base.

On Wednesday, the team of Americans found more footprints they believe to be Arnold’s at the crater’s rim near some deep ravines, according to a post at a Facebook Web site maintained by Arnold’s friends and family.

No belongings or other traces of the hiker has been found.

"What we do know is that Mr. Arnold went on one of the trails local residents use to climb the volcano," said Yuichi Taniyama, a spokesman for the Kagoshima Prefectural Police. "It is not an easy path. It has a rugged surface and huge rocks block the path here and there."

The American search party is expected to remain on the island until Saturday.

"From what the footprint experts said, we understand that Mr. Arnold went up to the top of Mount Shindake and walked down toward Mount Furudake, which is located to the southeast," said town official Hisashi Kawahigashi. "There is the possibility that he walked down a trail on the northeastern side of Mount Furudake. Had he taken a trail along the southwestern side, he should have been able to come back to a main road near the port.

Few residents ever enter the valley, because "there is no need or business for people to be there," Kawahigashi said in a telephone interview.

The only person ever lost to the mountain in recent memory was when an elderly island resident who suffered from dementia went missing more than 20 years ago, he said. His body was found after 13 days of searching.