LONDON -- London police say they have found the body of a missing 12-year-old schoolgirl in her grandmother's home and arrested the grandmother's partner on suspicion of murder.

A citywide manhunt was launched after Friday's grim discovery in the south London property.

Tia Sharp disappeared a week ago, and the search for her became a national news story. The Sun newspaper offered a 25,000 pound ($40,000) reward for her safe return.

Scotland Yard said 37-year-old Stuart Hazel, partner of Tia's grandmother Christine Sharp, was arrested in another district of south London after a member of the public identified him.

A senior policeman, Commander Neil Basu, says it took three searches of Sharp's home, and the use of sniffer dogs, to find the girl's body.