A federal indictment accuses Lori Drew, 49, of O'Fallon, Missouri, of using the social networking Web site MySpace.com to pose as a 16-year-old boy and feign romantic interest in the girl.
The girl, Megan Meier, committed suicide after her online love interest spurned her, according to prosecutors, telling her the world would be a better place without her.
Drew faces up to 20 years in prison on charges of conspiracy and accessing protected computers to obtain information to inflict emotional distress.
The indictment, which was filed in U.S. District Court in Los Angeles, accuses Drew and others of registering on MySpace as "Josh Evans" and using the account to lure Meier into an an online romance.
Authorities have previously said that Drew set up the account to find out what Meier, who lived in her neighborhood, was saying about her daughter.
Prosecutors allege that Drew and the others violated MySpace's terms of service by using false information to create the account so they could "harass, abuse or harm" Meier, according to the indictment.
The two corresponded for about four weeks before "Josh" broke off the relationship, authorities said. Within an hour, Meier hanged herself in her room and died the next day.
The indictment does not allege that Drew sent the final message telling Meier the world would be a better place without her. Instead, it blames her unnamed co-conspirators, who authorities have previously said include a teenage girl.
After Drew learned of the teen's suicide, the indictment alleges, she directed one of the teens involved to "keep her mouth shut" and deleted the account.
Meier's mother, Tina Meier, told CNN in November that her daughter had self-esteem issues and had struggled with depression since childhood.
She said when her daughter began receiving messages from "Josh" telling her she was pretty, she was thrilled.
When "Josh" broke off the relationship, Tina Meier said, her daughter was devastated.
"She was looking for me to help calm herself down like I always did and be there for her. And I was upset because I didn't like the
language she was using, and I was angry she didn't sign off when I told her to," Tina Meier told CNN. 
Watch Tina Meier's reaction to the charges
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"She said to me, 'You're supposed to be my mom, you're supposed to be on my side,' and then took off running upstairs," Tina Meier said.
Tina Meier found her daughter hanging by a belt shortly afterward.
"It's as if my daughter killed herself with a gun," Meier's father, Ron, told CNN. "And it's as if they loaded the gun for her."
Drew is scheduled for arraignment in June.
"This adult woman allegedly used the Internet to target a young teenage girl, with horrendous ramifications," U.S. Attorney Thomas P. O'Brien said in a written statement.
"Any adult who uses the Internet or a social gathering Web site to bully or harass another person, particularly a young teenage girl, needs to realize that their actions can have serious consequences," O'Brien said.
In December, Missouri prosecutors declined to file charges against Drew, saying there was no law under which she could be charged.
"There is no way that anybody could know that talking to someone or saying that you're mean to your friends on the Internet would create a substantial risk," St. Charles County Prosecutor Jack Banas said. "Under the law, we just couldn't show that."
