SARANAC LAKE — A coroner and medical examiner say a 28-year-old New Jersey hiker, whose body was found near Wallface Mountain Monday afternoon, died from bronchial pneumonia resulting from a lack of food, a constant wet environment and the cold.

These external factors all contributed to mucus building up in Alex Stevens’s lungs and bronchi, eventually killing him after two weeks in the wilderness — about three days before his body was found, Essex County Coroner Francis Whitelaw estimates.

“He had a striking amount of purulent material [pus] in his tracheal bronchial tree,” said local medical examiner Dr. C. Francis Varga, who conducted the autopsy at Adirondack Medical Center in Saranac Lake. “Diagnosis could have been made by a sixth-grader; it was that easy.”

Varga explained that we all carry disease-causing bacteria in our lungs which, when the immune system is under stress from cold and water, grow out of control.

Stevens had been last seen hiking on Sept. 2 as he made his way from the Upper Works trailhead to Wallface Mountain. A search began for him on Sept. 9, when he was reported missing by friends he was supposed to meet in New York City. In the week in between, nighttime temperatures ranged between 28 and 52 degrees, and rainfall reached over a half-inch on some days. While rain ended during the search, temperatures dropped again into the 30s at night and remained there steadily.

The autopsy revealed Stevens possibly had hypothermia as well, evidenced by stress ulcers found in his stomach. Varga said it looked as if Stevens’ hands had been submerged in freezing water. He had scrapes and bruises on his extremities from bushwacking, but there was no trauma to him otherwise.

Stevens, a resident of Hopewell, New Jersey, had set out for a three-day hike in the High Peaks Wilderness but was inadequately prepared for multiple overnights in rugged terrain in rainy fall weather, according to state forest rangers.

People who talked to Stevens on Sept. 2 near Wallface said he was wearing open-toed sandals, shorts, a T-shirt and a light backpack. Rangers said he had his cellphone, a blanket or bed roll, a hammock with a tarp that he could use to stay out of the weather, and some food.

Stevens was out of food when he was found, Whitelaw said, and a ranger search map showed he had discarded two of his water bottles.

“When people get a lack of nutrition, being weak and sick and everything else, any number of things could be going on in his head,” Whitelaw said. “Certainly your judgment is going to be way off, and you are going to do things that just absolutely don’t make sense, and that’s just what we find with a lot of these people.”

He did not have shelter but was carrying supplies for one, according to Whitelaw. He was not carrying a compass or tools to start a fire, and all his food was gone, the coroner added.

Tests being conducted currently will reveal which bacteria specifically was found in his lungs according to Varga.

Family members of Stevens drove up from New Jersey to the Saranac Lake hospital Tuesday and are beginning to make funeral arrangements, according to Whitelaw.