The body of Sol Pais, a student from Surfside, Florida, was found by authorities about 40 miles (64 km) west of Columbine High School, at about 10:30 a.m. local time, said Dean Phillips, special agent in charge of the Denver office of the Federal Bureau of Investigation.
The sheriff's Twitter post, which included two photos of Pais, said she was dressed in a black T-shirt, camouflage trousers and black boots.
Pais died from "an apparent self-inflicted gun shot wound", Jefferson County Sheriff Jeff Shrader said at a news conference Wednesday. One woman, who was hiking in the area, told CBS4 that she was told to leave the area because "a naked woman matching the description with a gun was spotted in the area running through the woods".
Pais was "no longer a threat to the community", Patricia Billinger, a spokeswoman for Colorado's Public Safety Department said. Upon her arrival, she legally purchased a pump-action shotgun at a gun shop near Columbine High School and then, seemingly, disappeared.
In Pais' hometown, Surfside Police Chief Julio Yero asked that the family be given "privacy and a little time to grieve".
Pais had apparently made disturbing comments about Columbine to friends and family and on social media, Phillips said, and was reported missing by her parents in Surfside, Florida.
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Dave Cullen, author of the bestseller "Columbine", spoke to Inside Edition about the latest threats against the schools.
We can confirm there is investigative activity around the base of Mt. Evans. The school is in Littleton, near Denver, and the woman was in densely-wooded snowy hillside terrain, at a campground in the foothills of the Rocky Mountains, in the Arapahoe National Forest.
John McDonald is in charge of security for the school district that includes Columbine.
Authorities said she did not threaten a specific school.
Miami-Dade Public Schools Superintendent Alberto Carvalho released a one-minute video to ease the minds of students and staff members. Police there said the parents aided in the investigation and provided valuable information that led investigators to Colorado. Saturday, April 20 marks the 20th anniversary of the Columbine tragedy, in which two students opened fire and killed 13 people. The Columbine killers have become a much-studied fascination for some disaffected teenagers and others who go on to become mass shooters.
Law enforcement has not confirmed Pais is the author of the journal.