CLAY COUNTY, Fla. -

Jarred Harrell, the man accused of killing 7-year-old Somer Thompson in October 2009, will plead guilty in a Clay County courtroom Friday to all charges he's facing in three cases, including murder, to avoid the death penalty, sources confirmed to Channel 4 Thursday afternoon.

Harrell would be sentenced to life in prison.

The Clay County Sheriff's Office said earlier Thursday there was the potential for "significant court action" at the 1 p.m Friday hearing in regard to pending prosecution of Harrell, and he will be present in the courtroom for the first time since he was arraigned in 2010.

"Should significant court action occur Friday as anticipated, personnel from the state attorney's office and Clay County Sheriff's Office will join members of Somer Thompson's family for public comment afterwards in the main courthouse lobby," a news release reads.

Harrell is accused of kidnapping, molesting and killing the Orange Park girl, and is also charged in unrelated cases of child molestation of a 3-year-old girl and possession of child pornography. He is facing a total of 59 charges.

His trial on the child molestation charges was delayed last month.

Diena Thompson, Somer's mother, said at her Orange Park home after last month's hearing that she's frustrated by the court proceedings, but she's willing to seek justice for her daughter, who was kidnapped while walking home from school and found dead in a southeast Georgia landfill three days later.

"I'm definitely frustrated that it gets pushed back, but if it's going to make justice happen and make it more profound, then that's exactly what I want to do," Thompson said of having to wait for Harrell's trial.

Sources familiar with the case said that Thompson was consulted about the plea agreement and that she will attend Friday's hearing.

Within hours after Somer's kidnapping was reported more than two years ago, hundreds of people -- many who had never met the girl -- joined the search. By the time her body was found, thousands who had never met Somer felt the loss.

The investigation into who killed Somer was frustratingly slow, but the Sheriff's Office was persistent.

On Feb. 11, 2010, Harrell, a former Orange Park resident, was arrested in Meridian, Miss., on 29 charges of possession of child pornography and was named a person of interest in the case.

That same day, Clay County detectives and the Florida Department of Law Enforcement searched a house in the 1100 block of Gano Avenue, not far from where Somer lived.

On March 26, 2010, Harrell was charged with murder in Somer's death.

"It begins, frankly, when they find pornography on a computer somebody has given to them," said Jacksonville attorney Dale Carson, who has watched the case from afar since Somer disappeared. "So there's only a remote connection with Harrell."

Carson gives credit to the Sheriff's Office in following the leads from child porn on a computer to finding out Harrell lived near Somer's home in Orange Park. Eventually, investigators found him at a relative's house in Mississippi.

"You've got to hand it to the Sheriff's Office in Clay County," Carson said. "They found the body up in Georgia. That, no doubt, added some DNA evidence to it. They ID him, bring him back here. They charge him. I think they have a really substantive case against him, a substantial case."

Details of the case have been under tight guard with a gag order in place.

State Attorney Angela Corey said in a statement Thursday that she "cannot talk about the Harrell case because of the gag order but will be able to talk about it tomorrow."

"So I have little doubt the family has spoken to the state attorney's office and has accepted whatever deal has been offered," Carson said. "Because if (Diena Thompson) had not accepted it, it would be political suicide for the state to not pursue it in a case like this."