Ms Drew has been charged under laws usually used against hackers
A US woman has gone on trial accused of using a fictional online personality to bully a 13-year-old girl who later killed herself.
Lori Drew, 49, allegedly posed as a boy on the MySpace website to befriend Megan Meier, who hanged herself after their virtual relationship ended.
California prosecutors say she set out to embarrass and humiliate the girl.
She denies conspiracy and three counts of accessing protected computers without authorisation.
The latter charges refer to a person who uses their otherwise legitimate access to a computer in an unauthorised way.
Prosecutors say Ms Drew violated MySpace's "terms of service" that prohibit users from using fraudulent registration information, using accounts to obtain personal information about juvenile members and using MySpace to "harass, abuse or harm other members".
The trial is being seen as a landmark internet law case.
Ms Meier, a neighbour of Ms Drew in Missouri and a former friend of her daughter, took her own life in October 2006.
It is alleged that she killed herself after receiving several cruel messages from a fictitious 16-year-old boy named Josh Evans, including one saying the world would be better off without her.
Prosecutors say Ms Drew and several others created the boy on MySpace, the social networking website, after Ms Meier fell out with her daughter.
In his opening statement, prosecutor Thomas O'Brien said the evidence would show that Ms Drew opened the online account and "fully intended to hurt and prey on Megan's psyche".
"Her purpose was to tease Megan Meier, to tease her, to humiliate her and to hurt her," he said.
Ms Drew is being charged under the Computer Fraud and Abuse Act - usually used against computer hackers, as prosecutors were unable to find any existing laws within the state of Missouri under which she could be tried.
Federal prosecutors in California claimed jurisdiction because MySpace has operations in Los Angeles.
MySpace users create their own profiles online
Defence lawyer Dean Steward told jurors that Ms Drew had not violated the computer fraud act, and reminded them she was not facing charges related to the suicide.
After jurors had gone home for the day, he unsuccessfully requested that a mistrial be declared, on the grounds that the emotional testimony was "totally improper in a computer fraud case".
Each of the four counts against Ms Drew carries a maximum five-year jail term.
The trial has been acknowledged as the first time the federal statute on accessing protected computers has been used in a social networking case.