WINTER HAVEN, Florida (CNN) -- The mother of a 14-year-old Florida girl accused of bullying a classmate who later committed suicide is facing child abuse and child neglect charges in a separate case, authorities said Friday.
Polk County Sheriff Grady Judd said 30-year-old Vivian Vosburg was arrested Friday afternoon.
The move came as investigators are still looking into what exactly drove 12-year-old Rebecca Sedwick to her suicide last month, a case in which Vosburg's daughter was charged with aggravated stalking. Police have also arrested a 12-year-old girl.
Judd made it clear that Vosburg's charges are not related to those against the teenagers.
Vosburg's arrest came after authorities received tips from residents that she might have been involved in beating children, Judd said. A minute-long video clip Judd played at a Friday press conference showed a woman, whom he identified as Vosburg, punching two boys with her fist while shouting profanities. The video had been posted to the Internet.
After being arrested, the mother first said the beating was an accident but then said it "got out of hand" partly because she was having a bad day, Judd said.
It wasn't immediately clear who took the video or when and where it was taken. It has since been taken off the Web.
Judd said criminal investigations on both the stalking and abuse cases are underway while Vosburg remains in jail.
The 14-year-old's father, Jose, told CNN's "New Day" on Wednesday that his daughter has an alibi. Jose did not want his last name revealed to the public.
Months of cyberabuse reportedly drove Rebecca to climb up the ladder of a pair of silos at an abandoned concrete plant in September. She had already cut open her wrists in December but survived that suicide attempt.
Weeks after Rebecca leaped to her death, an incriminating message appeared in the Facebook feed of the estranged 14-year-old friend, who was accused of being Rebecca's main tormenter.
"Yes IK I bullied REBECCA nd she killed her self but IDGAF," the message posted Saturday on Facebook read. Judd said the online vernacular meant: "I don't give a (expletive)."
The sheriff called the girl and her family in to see him about the post. Police arrested the daughter.
"She forced this arrest," Judd said.
The 14-year-old couldn't have been the one to post that message, her father told CNN's Chris Cuomo.
The father had just finished watching the news on TV when he found her asleep and sent her to bed. It was about that time that the note landed on Facebook, he said.
"I grabbed the computer and took it to my room, and the only other thing she could have used to send this message was this cell phone, and my cell phone is always with me," he said.
He suspects someone hacked her account.
But the sheriff said he doubts that. Investigators don't believe the teen's Facebook account was compromised, Judd said earlier.
Over a boy?
Rebecca and her alleged bully were once friends, but they both had feelings for the same boy, police said. It soured their relationship.
The allegedly angry friend is not the only accused bully. Police confiscated the laptops and cell phones of 15 girls at Crystal Lake Middle School, which Rebecca had attended.
They found a barrage of horrible messages:
"nobody cares about u"
"i hate u"
"you seriously deserve to die"
The bullied girl gave up on herself, Judd said. "Rebecca wasn't attacking back. She appeared to be beat down."
Rebecca's suffering was no secret at her school. Teachers saw her in tears. There were fights, the sheriff said. In December, she was hospitalized after slitting her wrists.
Her school started a campaign against bullying, giving talks before the student body to discourage it.
The night before her deadly plunge, she sent a message to a boy she met on Facebook: "I'm jumping. I can't take it anymore."
The girl's defense
The attorney for the 14-year-old stands by her father's alibi.
Her client isn't responsible for the controversial post that led to her arrest, said Andrea DeMichael. The teenager has insisted to her that, "This is not as clear-cut as it seems."
The 14-year-old's parents said they regularly check the online activity of their seven children, including their teenage girl's.
"I always check her Facebook. I know her password," Vosburg concurred on "New Day." She didn't see any vile messages. "If they're there, we didn't see it," she said.
But aside from that one incriminating message after Rebecca's death, the taunts reached her through other chat services, the sheriff said.
Her parents shook their heads and gave blank stares when asked about the other sites during the interview.
They never heard of them.
"The only one that she had was Facebook, to our knowledge," the father said.
DeMichael disputed there was any harassment.
She said the 14-year-old and Rebecca did have a falling-out over the boy, and there was some "back and forth" at school between the former friends, but the girl never threatened Rebecca.
"She was actually upset at what happened to the victim," DeMichael said.
The 14-year-old's parents agreed.
John Couwels and Kim Segal reported from Winter Haven, Florida; and Ben Brumfield reported from Atlanta; and CNN's Marlena Baldacci, Kevin Wang, Steve Almasy and Sara Ganim contributed to this report.