Polk County Sheriff's Office via Reuters Rebecca Ann Sedwick, 12, jumped to her death from a third-story cement plant structure in central Florida on Sept. 10 after being verbally, physically and cyber-bullied throughout 2012 and 2013.

One of the two Florida girls accused of cyber-bullying a 12-year-old classmate who committed suicide said in Facebook messages released Friday that "no one [will] ever know the truth" because the girl "went to hell."

Rebecca Ann Sedwick died after jumping from a third-story cement plant structure on Sept. 10 after having been verbally, physically and cyber-bullied throughout 2012 and 2013, authorities said.

The 12- and 14-year-old girls — whom NBC News isn't identifying because they are juveniles — are charged with aggravated stalking. Both pleaded not guilty this week.

Authorities have said the 14-year-old confessed to harassing Rebecca on social media, and Friday, the Polk County Sheriff's Office released transcripts of Facebook chats the girls had with each other and with friends.

The 12-year-old girl consistently expresses remorse for any role she might have played, telling an unidentified friend: "Shes the only one i bullied and now i can't say i'm sorry...."

But the 14-year-old shows a very different tone in a long chat with another unidentified friend (all spellings and text shorthand are from the original):

Defendant: Cant believe Rebecca is dead , I thought they wouldn't find the body Friend: What r u talking about u thought they never find the body? Ik she died but what u mean by that Defendant: They found her body , I thought they weren't they "think" its sewcide hope it stays that way. Friend: Y u talking like that? What's wrong with u Defendant: No reason it was best for everyone that she went to hell , no one with ever know the truth

The 14-year-old girl had been scheduled for an arraignment Friday morning, but her defense attorney filed a written plea of not guilty, canceling the hearing. Her next court appearance is a pretrial conference scheduled for Tuesday.

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