Deschutes County and Lane County sheriff's personnel made the announcement on Monday, June 25, after consulting with Osborne's family.

Osborne was reported overdue and possibly lost or injured in the Three Sisters Wilderness area on Monday, June 18. Corwin was reported missing by his father, who had dropped him off at the Devils Lake Trailhead.

An immediate search was implemented by Deschutes County Search and Rescue. Lane County Sheriff's Office Search and Rescue was immediately contacted and advised of the situation. Lane County activated their Search and Rescue Team.

Over seven days, some 250 personnel from over 20 county, state, and federal agencies spent over 6,000 man-hours searching the Three Sisters Wilderness area for the lost hiker.

Osborne was described as an extremely fit outdoorsman who routinely covered long distances in his hikes. However, authorities also noted that he was lightly equipped with just some water, a space blanket and some food.

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According to John Miller of the Lane County Search & Rescue unit, conditions on the mountains are "what I would characterize as dangerous and nasty," with snow at 7,000 feet, which softens considerably in the afternoon sun.

Miller said there are numerous deep snow pockets in the area.

Osborne's trek was characterized as "aggressive" by Deschutes County search coordinator Joel McNamara. McNamara said the route over the three peaks can be conquered by a top-flight athlete in the mid-summer months. It is much more dangerous early in the season.

"People who travel solo in that area are taking a risk," Miller noted. "I believe Mr. Osborne knew what he was doing. He took that risk and may have paid the ultimate price."

The wilderness area was searched by foot, horseback, aircraft and specialized infrared heat sensing equipment. Over 150 square miles of wilderness was searched including 20 square miles of the summit elevation areas of the Three Sisters.

According to authorities, information and fliers will be posted at trailheads and, according to McNamara, mountain rescue crews will conduct training missions in the area in hopes of locating remains.

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Osborne was unmarried and had no children.