She found the letter this month, more than one year after her 13-year-old daughter died after consuming a lethal dose of Benadryl.

Undated and written in pencil, it was discovered tucked between sheets of blank paper inside a school binder, the kind kids use to put their academic life and assignments in some order.

“Dear Bullys,” the letter from Allison Trebesch starts out.

“I see all the mean things you say to people on ask.fm (an online chat site). You can say whatever you want people because it’s all (anonymous). You sit behind a computer screen and feel some kind of satisfaction of telling people to kill themselves or that they are ugly or something. It’s sick. One day someone will (commit) suicide and it will be because of you! Think about what you are doing to somebody. What will you do when (they are) gone?”

Something told Julie Dornseif on this day to open one of the boxes in the basement that contained her daughter’s belongings. She had never felt the need to open one before. The binder was in the first box she opened. She knows what compelled her to do it.

“It was Ally,” said Dornseif, a mother of three who works at the Minnesota Bureau of Criminal Apprehension as a forensics evidence specialist. “I have a picture of her on my nightstand. I looked at it that morning, and it was like she was telling me, ‘Mom, please go through my things.’ ”

The letter, which Dornseif believes was written shortly before her daughter’s death Sept. 17, 2013, reaffirmed accounts from classmates after the incident that her daughter had been bullied by anonymous posters on the online site, which is popular with teens.

“I will never know who bullied her on that site, and (at) this point it’s been a year, and the pain for our family is the same as the day she died, so we will let it go, as it won’t bring her back,” Dornseif told me.

“But with this letter, it was like she was asking me to share it, to alert parents and to tell kids that saying horrible things is not OK, that bullying is not OK, that words do hurt.”

KEPT IT TO HERSELF

The cause of death was a complete shock. Allison was smart, popular, pretty and athletic. Though a middle-schooler, she was a diver with the East Ridge High School swim team and competed with the Woodbury High School gymnastics team. In February 2013, eight months before her death, she became one of three seventh-graders to compete in the Class 2A state gymnastics meet.

Tragedy had visited her life. Two years earlier, her father, Tom Trebesch, took his life. Her mother and father divorced seven years ago.

“Two years have passed by but it’s felt (like)forever,” Ally wrote on her Twitter page on the second anniversary of his death on June, 3, 2011. “I miss you so much … I love you dad,” she added.

“Absolutely her dad’s death impacted her,” Dornseif said.

There was also a bullying incident the year before. Another parent informed school officials that Ally was being bullied on the online site.

“Of course I knew nothing of it, because she wasn’t that type of person, and when I asked her she was like, ‘Mom, please, everything is OK,’ so I let it go,” said Dornseif, who is also program director for the Woodbury Community Ed Gymnastics/Maga Team. “My daughter was not the type of kid that would ever tell me if anything was wrong.”

Things seemed normal the night before her death. Ally did her homework and set her alarm clock as well as the clothes she planned to wear for school the next day. She did have a conversation with her boyfriend around 10:30 p.m.

“Their conversation was about his parents getting a divorce, and he was upset about it, and she was saying, ‘It’s going to be OK, be strong,’ ” Dornseif recalled. “She said nothing else other than she was upset about something someone had said about her, (but) she wouldn’t tell him what it was.”

The boy tried to call and then text around midnight but did not get a response.

‘I NEVER SAW THIS COMING’

Dornseif and her youngest daughter, Olivia, now 13 and also an accomplished gymnast, found Ally unresponsive on her bed and called police. The medical examiner estimated Ally died about 3-1/2 hours before she was found.

The family moved to another home, hoping it would help ease the pain. Dornseif has a major regret in hindsight.

“She never ever let me see her phone or laptop, and I respected her privacy,” she said. “Now I wish I had made her not lock it all the time.”

Another girl confirmed the cyberbullying after Dornseif posted the letter on both her and Ally’s Facebook page. Although she has the know-how and resources to do it, she has no interest in checking her daughter’s ask.fm account to determine who were the culprits. She has her suspicions, which center, she believes, on “jealousy.”

She has read postings from other teens and “it’s pretty horrible the things they say — You are fat, you are ugly, I hope you die.”

She hopes the letter, which remains in the school binder, is a wake-up call to parents and youths.

“I just don’t want any parent to go through what I have gone through or my family, as the pain is as bad as it was the day it happened,” she said. “I was extremely close to Ally, and I never saw this coming.”

She finds solace and strength through her surviving daughters and by coaching young gymnasts.

“I’m thankful,” she wrote in an email. “Every day is a blessing. Don’t take life for granted, because you never know, life can change in an instant and will never be the same.”

RubÃ©n Rosario can be reached at 651-228-5454 or rrosario@pioneerpress.com. Follow him at twitter.com/nycrican.