UPDATE: Officials scale back search team Wednesday after 5 day effort.

Trackers with dogs are combing part of Joshua Tree National Park in California, searching for Paul Miller, 51, of Guelph Ont. reported missing since heading out for a hike Friday morning.

Please Retweet <a href="https://twitter.com/hashtag/California?src=hash&ref_src=twsrc%5Etfw">#California</a>! My family friend Paul Miller is missing! Anyone at <a href="https://twitter.com/hashtag/JoshuaTreeNationalPark?src=hash&ref_src=twsrc%5Etfw">#JoshuaTreeNationalPark</a> - Contact local authorities and be on the look out if you’re in the park area!! Please retweet: <a href="https://twitter.com/hashtag/FindPaulMiller?src=hash&ref_src=twsrc%5Etfw">#FindPaulMiller</a> link is here: <a href="https://t.co/soigT1C3Rg">https://t.co/soigT1C3Rg</a> <a href="https://t.co/PoOOSqJWVl">pic.twitter.com/PoOOSqJWVl</a> —@CamGuthrie

The search for Miller is focusing on the 49 Palms Oasis trail, located in the southern area of the vast desert park about 150 miles (241 kilometres) east of Los Angeles.

"We haven't found anything — no articles of clothing, discarded water bottles, or food wrappers, or anything like that, it's very unusual," George Land, public information officer of Joshua Tree National Park told CBC.

The National Park Service says Miller departed for the hike at 9 a.m. Friday and his wife reported him overdue at noon. His car was found at the 49 Palms Oasis trailhead.

Land said the search efforts have escalated since Friday afternoon, when they started with 30 people. As of Tuesday afternoon, they are 90 searchers, six canine teams, an all-terrain vehicle and a helicopter looking for Miller.

"We're getting into crunch time, it's getting to be a critical situation if Mr. Miller is in fact in the park so we're throwing every resource we have at it to find this gentleman and bring him back to his loved ones," Land said.

Land said Miller's case is "uncommon" as the park has 3.1 million visitors per year.

"It's a hike where you hike straight into the Oasis and hike the same trail back out and so it's not a trail where people get lost on or turn around on," he said.

Land said crews will continue searching and if they don't find anything by Tuesday evening, they might have to scale back efforts.

"When there's someone lost, the search never ends," he said. "What does happen is that we have to reduce resources, it's not sustainable to have that many people out... in the number that we do."

Summertime temperatures can surpass 37 C (100 F) in the park.