( CNN ) -- The news was devastating , the aftermath surreal . Somer Thompson , 7 , went missing Monday on her way home from school . Diena Thompson clutched a tissue in her right hand , frequently wiping her eyes as she told reporters that she could n't believe it was her daughter whose body was found in a Georgia landfill . Her visage revealed the weight of grief and a yearning for justice . Standing outside her home in Orange Park , Florida , Thompson looked into the camera and , with her voice cracking , sent out a stern warning to her daughter 's killer . `` I want you to know that 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 . You do n't take from somebody . You did n't just take her from me . You took her from my family , you took her from all these people . And you do n't do this to a little baby and put my baby in the trash like she 's nothing . That 's not OK , this is not OK. '' Watch Thompson warn her daughter 's killer » . The body of her daughter , 7-year-old Somer Thompson , was found in a south Georgia landfill , Clay County , Florida , Sheriff Rick Beseler said Thursday morning . Authorities on Friday were combing were through a `` tremendous mountain '' of garbage at the landfill , a sheriff 's spokeswoman said . Some possible evidence has been removed from the landfill , but authorities wo n't describe what they found , said Mary Justino of the Clay County Sheriff 's Department . Police have no suspects , she said . She said other law enforcement teams are focusing on the locale where the child apparently was last seen . Justino said witnesses , including some children , saw her on the sidewalk in front of a vacant house that is being renovated after a fire . `` Since Monday , we have been trying to figure out who frequents that area , '' including anyone working on the home , she said . Authorities are treating the death as a homicide . Somer became separated from her siblings and schoolmates on her way home from school in Orange Park , Florida , on Monday . She was seen in a fight at school before she disappeared , according to a police report released Thursday . Her 10-year-old sister told police that Somer had gotten into a fight with another girl at school earlier in the day . The sister said she brought up the fight while she and her brother walked Somer home from school , and that Somer ran off from them , apparently upset . The sister said she lost sight of Somer in a group of other kids leaving the school , according to the police report . The medical examiner in Savannah , Georgia , used dental records to positively identify the body as Somer 's , said Clay County Sheriff 's Office spokeswoman Mary Justino . Authorities now are turning their full attention to finding the child 's killer . Beseler held up a map dotted with markers as he said on CNN 's `` American Morning '' that detectives have questioned more than 70 registered sex offenders or predators living within five square miles of Somer 's home . The landfill where her body was found is near Folkston , Georgia , 55 miles north of where the girl became separated from her schoolmates on her way home from school in Orange Park on Monday . The sheriff told the girl 's mother Wednesday night that her daughter had been identified . Thompson , he said , was devastated . `` 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 , '' Beseler said at a Thursday morning news conference . Watch sheriff announce that girl 's body identified » . Authorities will work to pinpoint where the garbage load that contained the girl 's body came from , Beseler said . The garbage that was brought into that part of the landfill was collected in the Orange Park area , he had said Wednesday , noting that authorities routinely search garbage when a missing person case has been initiated . The investigation has now turned into a murder probe . `` There is a child killer on the loose , '' the sheriff said . `` I fear for our community until we bring this person in . '' Rewards totaling $ 30,000 have been offered for information leading to the arrest and conviction of whoever is responsible . CNN 's Maria P. White contributed to this report .
NEW : Authorities remove `` evidence '' from landfill where girl 's body found . Somer Thompson was in fight at school on day she disappeared , police say . `` I hope they get you '' is grieving mother 's message to killer . Score: 6