For weeks, 24-year-old Jarred Harrell was observed scurrying from his shed to various areas of his backyard in the early morning. Sometimes he was dressed only in what neighbors described as short silk boxers and a gray sweatshirt.

According to a woman who lived next door, Harrell, who moved to the home in Callahan, Fla., at the start of the year, acted strangely from the start.

"He would run from the shed back there, and just run back and forth, back and forth. He'd be out there sometimes 5:00, 5:30 in the morning just running," said the neighbor, Christie, who asked that her last name not be used.

"He had on like these really short... short silk... things, they kind of looked like boxers. And a gray sweatshirt, 'cause we would laugh at how he was dressed," said another neighbor who asked to be identified as Jackie.

They say he'd run for hours.

"Just like crazy running, like a kid would run when they're mad," said Christie.

As it turns out, Jarred Harrell probably had a lot on his mind. He was fast becoming a person of interest in the murder of young Somer Thompson, who vanished while walking home from school in Orange Park, Fla., on the same block where Harrell reportedly had been living at the time.

The 7-year-old girl, whose body was found in a Folkston, Ga., landfill after her October 2009 abduction, was also in Rod Buchannan's thoughts.

Scared, because they knew the owner of the car was Jarred Harrell, someone with a dark past that they had come to fear. He was their daughter's former housemate and, from what they knew about him, the fact that he was living just three houses down from where Somer was last seen was reason for concern.

Buchannan said that less than a year earlier his son had accidentally stumbled onto Harrell's terrible secret.

"He got onto Jarred's computer one day to play a game," Buchannan said. "There was an icon on the desktop, that said, it was either 'Child Penetration' or 'Toddler Penetration.' As he turned around, Harrell came back up, and reached around and turned the computer off. And told him not to get back on the computer without his permission."

But what the Buchannans discovered later on Harrell's computer would leave no room for doubt. Harrell's mother had asked if her son could move into an apartment complex with the Buchannans' daughter and her fiancé to help him get on his feet and share expenses. Harrell did so, but the arrangement did not last long.

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"He would run from the shed back there, and just run back and forth, back and forth. He'd be out there sometimes 5:00, 5:30 in the morning just running," said the neighbor, Christie, who asked that her last name not be used.

Click HERE for a map of registered sex offenders near the school Somer Thompson attended.

Click HERE for photos from the Somer Thompson case.

"He had on like these really short... short silk... things, they kind of looked like boxers. And a gray sweatshirt, 'cause we would laugh at how he was dressed," said another neighbor who asked to be identified as Jackie.

John Albert Gardner III, who spent five years behind bars for punching and molesting a 13-year-old neighbor, pleaded guilty to the murders of Chelsea King, 17, and Amber Dubois, 14, San Diego District Attorney County spokesman Paul Levikow confirmed. Dubois spent time in Orange County with her father, who lives in Buena Park.In what was supposed to be a routine case status hearing Friday, Gardner pleaded guilty to killing the two girls. In exchange, he will be sentenced to two life terms in prison instead of being eligible for the death penalty. The plea bars him from filing an appeal.

Gardner had pleaded not guilty in March to killing and raping King. But an indictment of Gardner in the death of Dubois had been kept quiet.

King, an honor student at Poway High School, disappeared Feb. 25 while jogging near Lake Hodges in northern San Diego County.

Her disappearance sparked a massive manhunt for the popular high school runner who frequented the trails near Lake Hodges. Her parents appeared on national television begging for the return of their daughter.

Gardner was arrested three days after King disappeared, but the teenager remained missing.

On March 2, police found King’s body in a shallow grave near the lake’s shore. She also had been raped. Four days later, Dubois’ skeletal remains were found buried in a remote Pala area northeast of Escondido. Dubois disappeared Feb. 13, 2009, while walking to Escondido High School.

Hundreds of volunteers had spent months combing through northern San Diego County searching for Dubois without progress. It was only after Gardner’s arrest that police were able to find her remains in rugged territory, leading to speculation that Gardner led authorities to her grave.

Jarred Harrell's Computer

Scared, because they knew the owner of the car was Jarred Harrell, someone with a dark past that they had come to fear. He was their daughter's former housemate and, from what they knew about him, the fact that he was living just three houses down from where Somer was last seen was reason for concern.

Buchannan said that less than a year earlier his son had accidentally stumbled onto Harrell's terrible secret.

"He got onto Jarred's computer one day to play a game," Buchannan said. "There was an icon on the desktop, that said, it was either 'Child Penetration' or 'Toddler Penetration.' As he turned around, Harrell came back up, and reached around and turned the computer off. And told him not to get back on the computer without his permission."

But what the Buchannans discovered later on Harrell's computer would leave no room for doubt. Harrell's mother had asked if her son could move into an apartment complex with the Buchannans' daughter and her fiancé to help him get on his feet and share expenses. Harrell did so, but the arrangement did not last long.

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