In 1999, twin sisters Kristin and Candace Hermeler, of Australia, wrote a letter to Brooks Brown, a former Columbine High School student once “targeted” by Eric Harris, who along with Dylan Klebold killed 13 and injured 23 during a school-shooting spree that year. “Thank you for not judging and for accepting Eric and Dylan, who were, from what I have heard, rejected and victimized by so many others. Thank you so much. Sincerely, Kristin,” read one letter (via CBS4).

The 29-year-old Hermeler sisters traveled to Colorado recently, where they simultaneously shot themselves in the head on the shooting range at Cherry Creek State Park (Kristin died and Candace survived).

In an interview with The Denver Post, Brown recalls the letters Kristin sent as “very sad.” “It was her wanting to know why it happened, trying to understand,” he says of the Columbine shootings. Brown–who communicated with Kristin vie phone, letters, and e-mail–says both sisters told him they had been bullied “physically and mentally,” but he later lost touch with them. Westword talks further with Brown’s mother about the connection.

In the 1970s, the Hermeler family moved from South Africa to Australia, where the twins were born in Melbourne. Former classmates at one school describe the women as intellectual but socially awkward, according to The Australian. One says the twins “were perceived as strange or weird. It was a bitchy school, and it was hard for them because they came in year 10. I can’t think of anyone who was actually friends with them.”