ORANGE PARK, Fla. -- As confirmation came Thursday afternoon that the body found in a southeast Georgia landfill is that of Somer Thompson, investigators are focusing on an Orange Park home where the 7-year-old girl was last seen.

Clay County Sheriff's Office spokeswoman Mary Justino said that Florida Department of Law Enforcement crime scene investigators were processing a vacant, burned-out home on Gano Avenue where witnesses last saw Somer. There they continued to search for evidence throughout the night.

The house is about 500 yards from Grove Park Elementary School and not far from where Somer ran off from her twin brother and older sister about 2:45 p.m. on Monday.

"Since it is the last-known area where Somer was scene, we have obtained permission from the homeowner to go in and process it," Justino said.

Investigators also searched for evidence in a public restroom at the Orange Park Athletic Association across the street from the house.

This news came as the Georgia Bureau of Investigation reported the autopsy was complete and positively identified the body found Tuesday afternoon in trash that had been hauled to the Chesser Island Landfill in Charlton County, Ga., on Tuesday.

The manner and cause of death was not disclosed due to the ongoing investigation.

Justino said that between efforts in Orange Park and at the Charlton County landfill, about 50 Clay County deputies are working full-time on this case.

Detectives in Orange Park said they were working their way through 561 leads. Justino said of the 160 registered sex offenders within a 5-mile radius of Somer's home, five of them had not yet been located and interviewed by investigators.

Detectives in Georgia were sifting through 225 tons of trash and garbage deposited by nine trucks that came from Orange Park.

"It is a huge undertaking, and we are committed to going through each and every part of that mound," Justino said. "Anything of evidentiary value will be found before our staff returns home -- we are committed to that."

At a news conference Thursday afternoon, Diena Thompson, Somer's mother, thanked everyone who has provided help and support for her family. She also had a message for the person who may have taken and killed her daughter.

"I will not sleep until this person is found. I hope they get you, and I hope they make you pay for a long, long time," Thompson said. "You don't take from somebody. You didn't take her from just me, you took her from my family, you took her from all of these people. And you don't do this to a little baby and put my baby in the trash like she's nothing. That's not OK. That's not OK. ... Watch out. We're coming. We're going to get you."

Somer's father, Sam Thompson, talked to a North Carolina TV station Thursday about his daughter's death.

"I'm so angry I can't express with words," Thompson said. "They disregarded my child like a piece of trash. I hope they crucify him. I forgive them for what they've done because the Lord says I have to, but as far as what I'm feeling, it's pure anger. I'm trying to get over that. There's some really sick people in this world."

In announcing the tentative identification before dawn on Thursday, Clay County Sheriff Rick Beseler urged people to be careful until they find who killed Somer.

"There is a child killer on the loose, and we're not going to rest until we catch this person and bring him to justice," Beseler said.

Beseler said he got a call about the visual confirmation on the body about 9 p.m. and called Somer's mother, Diena Thompson.

"Needless to say, she was absolutely devastated," Beseler said. "It was the hardest phone call I've ever had to make in my life, and I hope I never have to make another one like that."

While Clay County detectives are at the Chesser Island Landfill just south of Folkson, an FBI forensic unit is the lead agency in processing evidence at the scene. The Georgia Bureau of Investigation and Charlton County Sheriff's Office were assisting.

Somer disappeared while walking home from school Monday afternoon. A massive search of Orange Park had been under way since Monday evening.

The Justice Coalition has offered a $30,000 reward for information for the capture and conviction of whoever is responsible for putting Somer's body in the trash.

Beseler said Dumpsters in the area are emptied on Tuesdays, and that particular garbage investigators were searching was dropped off Tuesday afternoon.

"It we had not done this tactic, I believe that bodies would have been buried under hundreds of debris -- probably would have gone undiscovered forever," Beseler said.

Clay County Detective Bruce Owens, who the sheriff credited with the idea to search through the city's trash, spoke to the media Thursday morning.

"I knew that Tuesday morning, trash was being collected," Owens said. "I knew that if a truck was seen, it would probably be the best just to follow it ... so they could isolate it from the normal dump so they would have the opportunity to search."

Clay County school representative Darlene Mahla said grief counselors will be on hand Thursday morning for students and teachers at Grove Park Elementary School, where Somer went to school.

Anna Braddy, whose daughter Kayla is best friends with Somer, said she took Somer to school the day the 7-year-old disappeared. Braddy said it was a normal morning and Somer was her usual self.