Police recovered the body of an eight-year-old girl in the district's Sreepur upazila around midnight on Thursday, about four hours after she went missing from near her home.
Law enforcers suspected that criminals might have killed Nilima after raping her.
Victim's family members said the girl went missing from near her home in Joinabazar Abdar village around 8:00pm.
After searching for hours, Nilima's relatives found the body near a lane beside Abdul Awal College.
Police later recovered the body from the spot and sent it to Shaheed Tajuddin Ahmad Medical College for an autopsy.
Law enforcers detained Parvez, 12, from his home in the same village, in connection with the incident. Nilima along with her parents lived in a rented house owned by Parvez's uncle.
Moniruzzaman, sub-inspector of Shreepur Police Station, said there were injury marks on the victim's body and bruises on her head.
On December 3 last year, Mousumi Akter, a first grader at a madrasa, was found dead in Sreepur's Uttarpara area. Police suspected that criminals killed the victim after raping her.