Mount Marcy is seen from Mirror Lake in the village of Lake Placid on Sunday. (New Photo - Chris Gaige)

KEENE — State Police released the name and cause of death of the person who died while hiking Mount Marcy on Thursday.

Brianna L. Mohr, 21, of Brick, New Jersey, was found near Mount Marcy’s summit Thursday night by state Department of Environmental Conservation forest rangers and showed no signs of life, according to Trooper Brandi Ashley, a New York State Police public information officer.

The cause of death was determined to be hypothermia, Ashley wrote in a statement. An autopsy was conducted at Glens Falls Hospital on Saturday by Dr. Michael Sikirica, a forensic pathologist.

Mohr was hiking with a dog, which was found alive Thursday night and hiked out to safety by forest rangers. Ashley confirmed that the dog was uninjured.

Ashley said there was nobody else in the hiking party. An Instagram account in Mohr’s name appears to show that she was a frequent hiker, including several past winter trips in the Adirondacks and elsewhere across the country.

The DEC led the incident response and State Police and the Essex County Coroner were subsequently notified.

The rescue attempt began when Mohr called 911 at 3:05 p.m. on Thursday, stating that she had slipped near the mountain’s summit and was unable to get back on the trail. The authorities have not said what caused Mohr to slip, or if she had been suffering from hypothermia or some other condition before the reported slip.

Given the nature of the emergency, DEC forest rangers responded with both ground and aerial search teams. The latter was assisted by the New York State Police’s Aviation Unit.

Two forest rangers attempted to spot the hiker from the State Police helicopter, but heavy cloud cover around Mount Marcy’s summit at the time prevented any sighting, according to a DEC spokesperson. At 6:06 p.m., one of the forest rangers who had been in the helicopter was inserted into the ground search operation at the Marcy Dam Outpost, which is about 5.1 miles away from and nearly 3,000 feet below the summit of Mount Marcy.

From there, the forest ranger hiked up towards the hiker’s last known location near Marcy’s summit, according to the DEC spokesperson. At 9:51 p.m., the ranger located the hiker, who was found deceased. It’s unclear if other forest rangers had been searching there earlier, or if that was the first forest ranger to make it up to the summit area.

Poor weather conditions at the time prevented rangers from being able to remove the body. Early Friday morning, a State Police helicopter was able to insert two forest rangers at the site and recover the hiker’s body.

“The New York State Department of Environmental Conservation offers its condolences to the family,” a DEC spokesperson said on Sunday.

At 5,344 feet, Mount Marcy is New York’s tallest peak. Its alpine summit is prone to extreme winter weather, such as low visibility from clouds and/or blowing snow, frigid wind chills and deep snow pockets that can form “spruce traps,” where hidden pockets of air develop as snow falls around the short summit pine bows, creating sink holes when stepped over.

Winter navigation can be especially difficult on exposed summits like Marcy, where strong winds can quickly blow in any preexisting set of snowshoe tracks. Thursday’s temperatures were in the teens and had fallen to the single digits, with a wind chill around zero, by 9 p.m. at Lake Placid’s New York State Mesonet weather station, which is located at 2,018 feet. Temperatures and wind chills were likely colder at higher elevations.

It’s unclear what trail conditions were like on Thursday. The DEC reported on Wednesday that the snow depth at its Lake Colden Interior Outpost cabin was 49 inches. The outpost is about 3 miles west of Mount Marcy and nearly 2,600 feet below its summit. Snow depth generally increases with elevation.