DENVER (KDVR) The death toll for the Columbine High School mass shooting in 1999 has risen by one.

Anne Marie Hochhalter, a survivor of the Columbine High School mass shooting, died on Feb. 16 at her home, according to her former principal, Frank DeAngelis. Hochhalter, 43, suffered two gunshot wounds during the massacre, where two seniors shot and killed 12 students and one teacher, then killed themselves. Another 21 people were injured by the gunfire.

The Jefferson County Coroner’s Office released a copy of her autopsy report on Wednesday.

The report stated that two gunshot wounds Hochhalter suffered in 1999, resulting in her use of a wheelchair in the 25 years since, likely turned into further issues and led to her death. The report said that Hochhalter died of “sepsis due to Streptococcus pyogenes.”

“Complications of paraplegia due to two remote gunshot wounds are a significant contributing factor,” the report stated. “The manner of death is best classified as homicide.”

Hochhalter’s family previously said that they suspected she died of natural causes stemming from her injuries in the shooting.

Hochhalter spoke out in 2016 in support of the mother of one of the shooters who released a book reflecting on the mass shooting, especially concerning her relationship with grief and battles with shame.

Hochhalter wrote at the time in a lengthy Facebook post that she wasn’t sure she would ever read the book, but said she had forgiven the mass murderer’s mother.

In 2012, Hochhalter also spoke publicly in support of the families and survivors of the Sandy Hook Elementary Shooting in Newtown, Connecticut.

“I really hope the good stories will come out and show a community can come together just like Littleton did after Columbine,” Hochhalter said. “I feel kind of helpless when I hear about these things and I want to help, I just don’t really know how.”

The Associated Press reported that Hochhalter struggled with intense pain from her gunshot wounds over the past 25 years. Yet her brother said she was tireless in her drive to help others from people with disabilities to rescue dogs and members of her family.

“She was helpful to a great many people. She was really a good human being and sister,” her brother, Nathan Hochhalter, said to The Associated Press.

Hochhalter attended the 25th anniversary vigil in April with her brother, who was trapped in a classroom during the shooting. She had not attended the 20th anniversary event because of post-traumatic stress disorder, she said in a social media post last year.

“I’ve truly been able to heal my soul since that awful day in 1999,” she wrote.

Others killed in the Columbine mass shooting were Rachel Scott, 17; Daniel Rohrbough, 15; William David Sanders, 47; Kyle Velasquez, 16; Steven Crunow, 14; Cassie Bernall, 17; Isaiah Shoels, 18; Matthew Kchter, 16; Lauren Townsend, 18; John Tomlin, 16; Kelly Fleming, 16; Daniel Mauser, 15; Corey DePooter, 17.

The Associated Press contributed to this report.