A hiker was found dead and his daughter remains missing after the duo attempted to hike to the summit of Maine’s highest mountain, officials said Tuesday. Search efforts are continuing in hopes to find her.

Tim Keiderling, 58, and Esther Keiderling, 28, left their campground in Baxter State Park at around 10:15 a.m. Sunday, intending to hike to the 5,269-foot summit of Mount Katahdin, according to the Maine Department of Inland Fisheries & Wildlife.

Park rangers launched a search for the Keiderlings Monday morning, after discovering their car still parked in a day-use lot on the grounds, according to the department. The rangers searched multiple hiking trails, including the Katahdin Tablelands where the hikers were last seen, but found no signs of the father or daughter.

Esther and Tim Keiderling Maine Department of Inland Fisheries & Wildlife

Officials said their probe expanded Tuesday, eventually involving more than 30 game wardens, the Maine Army National Guard, and a search and rescue team with a K-9 crew that joined three helicopters surveying the area from above.

The K-9 search team found Tim Keiderling’s body at around 2:45 p.m. Tuesday, Baxter State Park said in a social media post.

“We know that many of our social media followers share in our deep sadness for the family and friends of Tim Keiderling, and appreciate your support as a teams continue the search for Esther,” the post said.

Baxter State Park’s website describes the Katahdin Trails, which end at the summit of the mountain, as “a very strenuous climb,” regardless of the trail hikers choose to follow in order to get there. It also warns that 80% of search and rescues in the park happen on hikers’ descents rather than their ascents, and more than 75% of the most serious incidents, including deaths, happen because hikers left their trail.