DENVER (AP) — A Florida teenager obsessed with the Columbine school shooting had already died by suicide by the time authorities launched a manhunt for her after learning that she had traveled to Colorado just days before the 20th anniversary of the massacre, a coroner's report said Wednesday.

An autopsy summary by the Clear Creek County coroner estimated that 18-year-old Sol Pais likely died on April 15 — the day authorities said she flew to Denver from Miami. The FBI's Denver office said it learned of Pais' travel the following morning. Agents also learned the day after she died that Pais had gone directly to a gun store from the airport and purchased a shotgun and ammunition.

Pais was already dead of a self-inflicted gunshot wound by the time agents began retracing her steps, according to the coroner's initial autopsy findings.

Chief Deputy Coroner Harriet Hamilton said Wednesday that the office is awaiting test results before producing a final autopsy report.

The gun purchase and other warning signs, including Pais' past conversations about the 1999 Columbine shooting, led the FBI and local law enforcement to consider the young woman a potential threat to schools and issue a public warning about her, authorities have said.

Columbine and other schools tightened security the afternoon of April 16 and closed entirely on April 17 when authorities still had not located Pais. She never threatened a specific school, authorities said.

Her body was found on April 17 in the foothills west of Denver. Authorities knew Pais was last seen in the area on April 15 but it was unclear when she killed herself until the coroner's report Wednesday.

"Based on the information we had at the time, local, state, and federal law enforcement agencies, in conjunction with school districts in the Denver Metro area, took the necessary steps to ensure our communities, and particularly our students, stayed safe until there was no longer a threat," Jefferson County Sheriff Jeff Shrader said in a statement.

An FBI spokeswoman declined comment Wednesday.

The search for Pais came amid preparations for memorial events marking the Columbine shooting. Two teenage gunmen killed 12 classmates and a teacher at the high school in Denver's suburbs before killing themselves.

