A 12 and 14-year-old were arrested in a Florida bullying case after one of them admitted online over the weekend that she harassed a 12-year-old girl who killed herself last month. (Associated Press)

Authorities in Polk County, Fla., have arrested two girls, ages 12 and 14, who they claim are partly responsible for the suicide of Rebecca Ann Sedwick last month. Sedwick, 12, was bullied cruelly and at length by a group of her peers before she hurled herself from the top of a tower at an abandoned concrete plant, according to authorities, who said they made the arrests to protect other children:

[Polk County Sheriff Grady] Judd said he arrested the 14-year-old girl after she posted online Saturday that she bullied Rebecca and she didn’t care.

“We decided that we can’t leave her out there. Who else is she going to torment, who else is she going to harass?” Judd said.

Police also arrested a 12-year-old girl who is accused of bullying Rebecca. Both have been charged with felony aggravated stalking.

The sheriff’s office identified the two girls, but the Associated Press generally does not name juveniles charged with crimes.

Judd said the bullying began after the 14-year-old girl started dating a boy that Rebecca had been seeing.

She “didn’t like that and began to harass and ultimately torment Rebecca,” Judd said.

The 12-year-old girl was Rebecca’s former best friend, but Judd said the 14-year-old girl turned her against Rebecca. Other girls also stopped being friends with her for fear of being bullied, the sheriff said.

Authorities have said Rebecca was “terrorized” by as many as 15 girls who ganged up on her and picked on her for months through online message boards and texts.

Associated Press

The sheriff’s office gave a detailed account of Sedwick’s ordeal:

The 14-year-old girl had several arguments with Rebecca via Facebook, as well as verbal confrontations at school.

Witnesses told investigators that the girl sent messages to Rebecca, calling her ugly, telling her to drink bleach and die, and telling Rebecca that she should kill herself.

Rebecca was jumped in school and later bombarded with such hateful messages via a cellphone application as “You’re ugly,” “Why are you still alive?” and “Go kill yourself.”

In February, the 12-year-old was suspended from school after allegedly attacking Rebecca.

The sheriff’s office said the 14-year-old girl bullied anyone who was friends with Rebecca, making students fearful of befriending Rebecca.

Her mother decided to home-school her daughter and eventually Rebecca transferred to Lawton Chiles Middle Academy, but detectives found evidence that the bullying continued on her cellphone.

Orlando Sentinel

Authorities reportedly arrested the two girls after the older one admitted online to having bullied Sedwick.