The Latest on the investigation of a woman believed to have posed a threat to schools in Colorado (all times local):

9:40 p.m.

Columbine High School is moving ahead with ceremonies marking the 20th anniversary of an attack that killed 13 people, and the community is awaiting more details on what led a teenager allegedly obsessed with the 1999 shooting to buy a shotgun and kill herself in the snowy foothills nearby.

A religious service Thursday night kicked off three days of commemorative events leading to a day of community service projects and a ceremony Saturday at a park near the school.

An already tense time at the school was exacerbated after 18-year-old Sol Pais traveled to Denver from Miami on Monday and immediately bought a pump-action shotgun.

Her body was found Wednesday, about 24 hours after Columbine and other schools locked their doors in response to fears that she intended to carry out her own attack.

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9:20 a.m.

Colorado schools that were shuttered just ahead of the 20th anniversary of the Columbine school shooting have reopened, a day after authorities found the body of a young Florida woman who was obsessed with the shooting. Many schools imposed increased security measures when they reopened on Thursday.

The FBI said the body of Sol Pais was discovered Wednesday in mountains outside Denver with what appeared to be a self-inflicted gunshot wound.

Columbine and dozens of other schools were closed Wednesday because of fears that Pais posed a threat. About 500,000 students in the area that includes metropolitan Denver and Colorado Springs were affected.

Authorities say Pais never threatened a specific school but made troubling remarks to others about her "infatuation" with the 1999 shootings. The FBI also says Pais purchased a shotgun immediately after arriving in Colorado on Monday.

The school closures affected about 500,000 students.

Events planned to mark the anniversary of the 1999 Columbine attack will go on as scheduled throughout the week, including a ceremony near the school on Saturday.

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11:10 p.m.

Authorities want to ensure that a Florida teenager who was obsessed with the Columbine school shooting was acting alone as dozens of Denver-area schools plan to reopen following a region-wide hunt for the young woman.

The FBI said the body of Sol Pais was discovered in the mountains outside Denver with what appeared to be a self-inflicted gunshot wound on Wednesday, about 24 hours after Columbine and other schools locked their doors in response to fears that she intended to carry out her own attack.

Authorities say Pais never threatened a specific school but made troubling remarks to others about her "infatuation" with the 1999 shootings. The FBI also says Pais purchased a shotgun immediately after arriving in Colorado on Monday.

The anniversary of the Columbine attack is Saturday.