The grieving mother of a Missouri girl told a jury Wednesday how her daughter hanged herself with a belt after receiving cruel messages on her MySpace account, some of which were from a boy whose identity was later revealed to have been invented by a neighbor.

Tina Meier recounted how "Josh Evans" interacted online with her 13-year-old daughter, Megan, during the first day of the trial against Lori Drew, who is accused of taking part in the Internet hoax that prosecutors say led to Megan's suicide.

Meier said after a name-calling exchange between Megan, "Josh," and two other girls in October 2006, she told a sobbing Megan, who was being treated for attention deficit disorder and depression, that she wasn't supposed to be online and shouldn't have gotten into the argument.

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"The last words she said to me were 'You are supposed to be my mom, you are supposed to be on my side,"' Meier said as she tried to hold back tears.

Meier said she ran later upstairs and found Megan hanging in the closet with a belt around her neck. She died the next day.

Drew, 49, has pleaded not guilty to one count of conspiracy and three counts of accessing computers without authorization. Each count carries a potential sentence of five years in prison.

In his opening statement to jurors, U.S. Attorney Thomas O'Brien said Drew helped create "Josh's" false identity on MySpace to learn if Megan was spreading malicious rumors on MySpace about Sarah Drew, the defendant's then 13-year-old daughter.

O'Brien said the evidence will show Drew opened the MySpace account and "fully intended to hurt and prey on Megan's psyche."

For the first time, O'Brien disclosed what Megan wrote after allegedly receiving a message the day she killed herself that said the world would be better off without her. Megan sent a response saying, "'You are the kind of boy a girl would kill herself over,"' O'Brien said.

Prosecutors said it's the nation's first cyber-bullying trial and its results could set a legal precedent for dealing with the issue of online harassment.

Defense attorney Dean Steward told jurors Drew did not violate the Computer Use and Fraud Act — used in the past to address computer hacking — and reminded them she was not facing charges dealing with the suicide.

"This is not a homicide case," Steward said.

Before the trial began, Steward tried to get U.S. District Judge George Wu to forbid mention of the suicide. Wu rejected the request but instructed jurors the case is about whether Drew violated MySpace's terms of service, not about whether she caused Megan's suicide.

After jurors were dismissed for the day, Steward unsuccessfully requested a mistrial, saying the emotional testimony was "totally improper in a computer fraud case."

Prosecutors said Drew conspired with her daughter and Drew's then 18-year-old assistant, Ashley Grills, to invent "an attractive male teenager" on MySpace to find out what was being said about Sarah.

Meier said she was concerned about "Josh," who had contacted Megan in early September 2006 wanting to be her friend. She added she thought her daughter was developing feelings for "Josh," but when there was a conversation that may have had sexual overtures, Meier contacted local authorities about the teen boy.

"Something wasn't right," Meier testified.

Local authorities never pursued the incident, Meier said.

Steward countered it was Grills who set up the MySpace account and his client was driving home when the message about the world being a better place without Megan was sent. Grills has been granted immunity to testify.

The case is being prosecuted in Los Angeles because MySpace computer servers are based in the area.