A Missouri woman is accused of cyberbullying for allegedly posting photos and personal information of a teenage girl on the “Casual Encounters” section of Craigslist after an Internet argument.

Prosecutors said 40-year-old Elizabeth A. Thrasher posted the 17-year-old’s picture, e-mail address and cell phone number on the Web site in a posting that suggested the girl was seeking a sexual encounter.

St. Charles County Lt. Craig McGuire said Tuesday that the victim is the daughter of Thrasher’s ex-husband’s girlfriend. The girl, who has not been named, received lewd messages and photographs from men she didn’t know and contacted police.

Thrasher, of St. Peters, is the first person charged with felony harassment in St. Charles County under a law passed in Missouri after the suicide of 13-year-old Megan Meier, who was the victim of an Internet hoax in a nearby community that drew international attention.

Thrasher was freed on $10,000 bond, but the judge barred her from having a computer or Internet access at home. No one answered the door at her house in a neighborhood about 25 miles northwest of St. Louis. Neighbors said she and her two children had just moved in recently.

Her attorney, Michael Kielty, said what Thrasher was accused of was no different from someone posting a number on a bathroom wall, telling people to “call Jane Doe for a good time.”

“It may be in poor taste. It may be inappropriate, but it’s not criminal behavior,” Kielty said. He said the state law was poorly written and Thrasher was devastated by the charges.

Authorities said Thrasher and the 17-year-old’s mother had been arguing, and there was some back-and-forth bickering on MySpace among all three. “Who started what is up for debate,” said St. Charles County Prosecutor Jack Banas.

McGuire said Thrasher then created the posting on Craigslist — whose “Casual Encounters” section warns that the pages may include adult content — that included the teen’s picture, employer, e-mail address and cell phone number. She received calls, e-mails, text messages and pornographic photos to her cell phone, police said.

If convicted of felony harassment, Thrasher could face up to four years in state prison, or up to a year in county jail, and a $5,000 fine, Banas said.

Under the harassment law that took effect last August, a cyberbullying offense can be charged as a felony if a victim is 17 or younger and the suspect 21 or older. Misdemeanor cases have been filed since then.

The law was spurred by the Megan Meier case, in which an adult neighbor, her daughter and a friend were linked to a MySpace page concocted to appear to be that of a teenage boy. “Josh” initially flirted with Megan but then made hurtful comments shortly before she hanged herself.