A grand jury returned a four-count indictment against Keith Matthew Emerald, 32, alleging he started a fire Aug. 17, 2013, and it spread beyond his control and turned into the massive Rim Fire.

The fire raged for two months across 400 square miles of land. The wildfire also ranks as the largest in the Sierra Nevada’s recorded history. The costs of fighting it totaled more than $125 million. Federal prosecutors said temporary fire restrictions in place at the time prohibited fires.

Investigators said Emerald, who has not been arrested, has at times admitted to starting the fire and other times denied it.

Hunting for deer with a bow that day, he initially told investigators that he caused a rock slide that sparked the fire, according to a search warrant affidavit for sites, including his house. He then allegedly suggested it was started by marijuana growers in the area.

After multiple interviews, he acknowledged starting a fire and cooking a meal. He burned trash from his backpack, but some of the embers blew uphill and set the brush on fire, he allegedly told investigators in a handwritten statement with some misspellings.

“The terrain was almost vertical, so I physically couldn’t put it out,” he wrote.

He expressed concern about possible community retaliation if his name were disclosed.

He was picked up by a rescue helicopter from the Clavey River Canyon area of the Stanislaus National Forest about an hour after the fire was reported, prosecutors said.

A resident of Columbia, a town in the Sierra Nevada foothills, Emerald is also charged with lying to a federal agent by saying he did not set the fire. A call to his attorney, federal public defender Janet Bateman, was not immediately returned.

Prosecutors said no court date has been set for his arraignment.

Authorities previously said the wildfire was started by an illegal fire set by a hunter, but they withheld the hunter’s name pending further investigation.

“The Rim Fire was one of the largest in California history and caused tremendous economic and environmental harm,” U.S. Attorney Benjamin Wagner said in a written statement. “While those harms cannot be undone, today we have brought criminal charges relating to the cause of the fire.”

The charges were the result of an investigation by the U.S. Forest Service and the Tuolumne County district attorney’s office, Wagner said.