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The nearly four-month-old investigation into the disappearance of Florida toddler Caylee Anthony culminated Tuesday in the arrest of her monther on a charge of first-degree murder, even though the girl's body hasn't been found.

A 19-member Florida grand jury issued indicted Casey Anthony, 22, on that and other charges in an indictment issued Tuesday afternoon, and Anthony was arrested shortly afterward.

The other charges are aggravated child abuse, aggravated manslaughter and four counts of lying to investigators in the death of her daughter, State Attorney Lawson Lamar said. The mother is being held without bond.

Anthony had been waiting more than a dozen miles away and preparing to herself in, according to her attorney Jose Baez.

Police have called Anthony a "person of interest" nearly from the beginning of the investigation, in mid-July, but she recently was identified as a suspect.

The toddler was last seen in mid-June, two months before her third birthday, but the family didn't report her missing for another month. Police have said they think Caylee is dead, based on evidence of a decomposing body found in the trunk of a Pontiac her mother was driving.

A few hours before the indictment was issued, Anthony stood silently, sometimes crying, as her attorney told reporters his client is innocent.

"Casey is going through a nightmare and has been living a nightmare for the last seven months," Baez said. "I sincerely believe that when we have finally spoken, everyone, and I mean everyone, will sit back and say, 'Now, I understand. That explains it.'"

He said prosecutors and police "threw the kitchen sink at her a long time ago."

The grand jury heard evidence Tuesday about the charges against Anthony, including testimony from the child's paternal grandfather.

George Anthony was subpoenaed to testify about the odor of human decomposition coming from his daughter's white Pontiac, according to MyFOXOrlando.com.

"This is going to be very hard for me to do," an emotional George Anthony said outside the Orange County Courthouse before going in. "My focus is on my granddaughter — it always has been. ... Just pray for her. That's all I'm asking for."

His spokesman told reporters that he was doing the "unthinkable" by testifying in the case against his daughter and asked the press to be respectful of his privacy.

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The grand jury was also presented with evidence about the discovery of chloroform during the investigation and about hair samples and stains found in Anthony's trunk, MyFOXOrlando.com reported.

Casey Anthony, her attorney and her mother Cindy Anthony were all at the closed-door grand jury session before the 19-member panel.

In order to deliver a murder indictment, jurors had to agree on whether or not there was enough evidence to charge someone.

After George Anthony finished testifying and left the court, he and his spokesman said they could not legally comment on the nature of the grand jury testimony and proceedings.

FBI agent Nick Savage and Orange County Sheriff's Deputy Jason Forgery also testified Tuesday, about a police dog detecting the scent of human decomposition in Casey Anthony's car trunk, MyFOXOrlando.com reported.

The child's grandmother first called authorities in July to say that she hadn't seen Caylee for a month and that her daughter's car had a scent of decomposition.

Casey Anthony told authorities that she had left her daughter with a baby sitter in June, and that the two were gone when she returned from work. She says she spent the next month trying to find her daughter and didn't call authorities because she was scared.

Investigators immediately started poking holes in her story. The apartment where Casey Anthony said she had left her daughter had been vacant for months, they said. They said she also lied when she told them she had been working at an area theme park as a photographer.

Click here for a timeline of the case.

Click here for some of the documents released.

Click here for more from MyFOXOrlando.com.

The Associated Press contributed to this report.