PORTLAND, Ore. -- Even after another tip came up empty in the search for Riley Zickel, family members of the 21-year-old missing Portland hiker are refusing to abandon the search.

Over the weekend, Zickel's family received a tip from a helicopter pilot who has been helping with the search in the Mount Jefferson wilderness area.

The Marion County Sheriff's Office acted on the information and sent the Corvallis Mountain Rescue Team to ascend Mt. Jefferson and check a crevasse on the Jefferson Glacier in Linn County. Unfortunately, the search team found no signs of Zickel and was forced to turn back because of a snow storm.

On Saturday, the active search for Zickel was suspended after seven days,

Zickel departed on July 27 from Breitenbush Lake Road at the Pacific Crest Trail. He intended to hike for one day and return the following day to visit friends in Seattle. He was last seen on the Pacific Crest Trail just north of Jefferson Park, where he visited with another hiker.

An experienced hiker, Zickel brought enough provisions (food and supplies) to last four days. He also reportedly has a cellphone, but crews were not able to locate its signal.

The Marion County Sheriff's Office says all available leads have been exhausted.

"It is a very difficult decision to withdraw resources from this search. Our SAR teams and staff worked tirelessly to find Mr. Zickel," said Marion County Sheriff Jason Myers. "We're very grateful for the assistance provided by our public safety partners, and our thoughts and prayers are with Mr. Zickel's family".

More than 340 searchers spent about 5,000 hours and searched 350 square miles of the Willamette National Forest north and south of Mount Jefferson, according to the sheriff's office. The search focused on the area between Mount Jefferson, Jefferson Park, Park Butte and the surrounding areas.

Midway through the search, deputies were hopeful they had found a lead. On Aug. 3, they shared a photo from July 29 of a man standing next to a tent near Sprague Lake. However, a man told deputies later that day the picture was of him and not Zickel.

A hiker took this photo on Friday and gave it to search teams looking for Zickel.
A hiker took this photo on Friday and gave it to search teams looking for Zickel.

The sheriff's office has shared photos of similar items that are being worn or used by Zickel, including his tent and hat. See the photos here (tent) and here (hat).

GALLERY: Missing hiker Riley Zickel

Zickel's parents were both in Marion County and assisted with the search.

"He's a real enthusiastic kid. He's real positive, real likeable," said Robin Zickel, Riley's father. "And I think he just thought, 'This is so cool -- I'm just going to keep going.' That's what I'm hoping."

"I'm impressed with every single person I've met since we've gotten to Oregon," Robin Zickel said. "I'm extremely happy with the work that's being done and the crews are just extraordinary. I can't say enough to thank everyone."

The search for Zickel will remain open until he is found. Anyone with information regarding Zickel's whereabouts should call the Marion County Sheriff's Office tip line at 503-584-7724.

KGW's Sky 8 flew over the wilderness area on Aug. 1. Watch the Sky 8 footage here.