This combination of undated photos released by the Jefferson County, Colo., Sheriff's Office on Tuesday, April 16, 2019 shows Sol Pais.

An 18-year-old who authorities say had an "infatuation" with the 1999 Columbine High School massacre appears to have kept a journal online in which she wrote about suicide and guns, and alluded to "plans" she was making.

The woman, Sol Pais of Florida, flew from Miami to Colorado earlier this week, bought a pump-action shotgun and ammunition upon arrival and then disappeared off of their radar, prompting a massive manhunt. On Wednesday, a law enforcement official told NBC News she had been found dead.