HONOLULU, Hawaii -- Police continue to look for signs of a missing Japanese visitor as the search for Masumi Watanabe stretches into its eighth day.

The case has gained international attention with the Japanese media now on the island covering the woman's disappearance.

Watanabe, 21, was last seen walking up Pupukea Road on the morning of April 12.

Police are focusing their investigation on a truck they found.

The truck, belonging to Haouli Pest Control, has a GPS system, which detectives are trying to use to create a timeline of events.

A report of a strong smell brought officers to the road up to Pu-u O Mahuku Heiau, but it turned out to be the remains of a pig.

For the third day, volunteer hikers with the Hawaiian Mountain and Trail Club joined in the search for the woman.

Friday morning, one of the volunteers found a discarded pair of men's underwear.

"Now who would get rid of a nice clean [pair of underware] like this? Right? I mean it doesn't even look dirty," said Mabel Kekina, of the Hawaiian Mountain and Trail Club.

Kekina said people also reported seeing Watanabe as late as Thursday.

Over the past week, the massive search has stretched from Waimea to Kaneohe.

Police said they have questioned an employee with Hauoli Pest Control and seized his company truck and personal car. They asked that anyone who that saw the truck between April 12 and April 16 to contact authorities.

Watanabe's host family said her family -- who is from Japan -- is not doing well but are thankful for all the efforts to find her.

Residents on the North Shore said that despite the mysterious case, they are rallying behind the hope that Masumi Watanabe will be found.

"Now days its hard to tell who's out there -- who's good or bad as far as the North Shore. It's a pretty tight community, and there are people who are helping out to find the girl, and hopefully they do find her," Del Galicinao, owner of Del's Photo Lab and North Shore resident said.