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A federal jury was given the case Monday of a Missouri mother accused of conspiring with her daughter and an assistant to harass a 13-year-old girl on the Internet, allegedly precipitating the teen's suicide.

"Lori Drew decided to humiliate a child," U.S. Attorney Thomas O'Brien said. "The only way she could harm this pretty little girl was with a computer. She chose to use a computer to hurt a little girl, and for four weeks she enjoyed it."

Drew, 49, listened to the argument impassively. Her lawyer, Dean Steward, said jurors must remember she is not charged with homicide in the death of Megan Meier, who hanged herself after receiving a message that the world would be better off without her.

"If you hadn't heard the indictment read to you, you'd think this was a homicide case," he said. "And it's not a homicide case. This, ladies and gentlemen, is a computer case, and that's what you need to decide."

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The defense attorney insisted the only question is whether Drew violated the terms-of-service agreement of the MySpace social networking site. He said that Drew, her young daughter Sarah and assistant Ashley Grills never read the seven-page agreement.

"Nobody reads these things, nobody," he said. "... How can you violate something when you haven't even read it? End of case. The case is over."

Drew has pleaded not guilty to conspiracy and accessing computers without authorization. She could be sentenced to as many as 20 years in prison if convicted of all counts. The jury was scheduled to begin deliberations Tuesday.

Assistant U.S. Attorney Mark Krause, in closing arguments, said Drew was responsible for devising the plan to invent an imaginary boy called Josh Evans who would communicate online with Megan, the daughter of a neighbor and once Sarah's best friend. Prosecutors say Drew wanted to find out whether Megan was spreading rumors about Sarah.

The prosecution showed the jury the photo that was used on the fake MySpace profile — a bare-chested boy with tousled brown hair.

Krause said Drew told her daughter and the then-18-year-old Grills what to write, to make the messages "flirty."

In so doing, he said, she violated the MySpace rules.

"The rules are fairly simple," he said. "You don't lie. You don't pretend to be someone else. You don't use the site to harass others. They harassed Megan Meier."

Krause also said Drew was warned by others that what she was doing was wrong, and Grills herself told Drew it might be illegal.

"She knew she was violating the rules and yet she told these two kids to keep doing it," he said.

Both prosecutors made references to testimony that Megan had been under treatment for depression, and Sarah, in testimony before final arguments, said she was aware Megan had been taking medication and seeing a psychiatrist.

"The defendant knew that she was dealing with a troubled little girl who was extremely fragile, and yet she did it anyway," Krause said.

"It went beyond a simple prank," said Krause, "to get her so hooked on this young man that she would be crushed when she found out he didn't exist."

Steward, in his response, said Drew had little to do with the content of the messages and was actually out of her home on the day of the final message, which was sent just before the suicide. He also said the message, which was quoted through out the trial, has never been found but was actually sent via AOL, not the MySpace site.

"My client, Lori Drew, was not home when all the electronic nastiness was going on," he said.

Steward also attacked Grills, the prosecution's star witness, as untrustworthy because she testified under a grant of immunity.

"Grills, bless her heart, is pathetic," he said. "Grills is a sad character who carries a lot of guilt."

He also blamed Megan's mother, Tina Meier, for allowing her daughter to continue the MySpace conversation with the invented Josh Evans after she learned it was going on. He faulted her for allowing Megan to register on MySpace and for not watching closely enough.

O'Brien reminded jurors how the tragedy began. He said Grills received a message from Megan suggesting Drew's daughter was ugly and a lesbian, leading Drew to concoct the plan.

"She could have walked four doors down and told Megan's mother to knock it off," he said.