MERCED, Calif.—A manhunt was under way Saturday for a man wanted in the death of a child whose body was found inside a central California home during the search for a missing 8-year-old girl. The body was discovered at a home in Merced on Friday, several days after relatives of Sophia Mason told police in the San Francisco Bay Area city of Hayward that they had not had contact with the girl since December, and that she was known to stay at different locations between Hayward and Southern California. The missing person report led Hayward police to arrest the girl’s mother, Samantha Johnson, 30, on a warrant stemming from a case of child abuse in Alameda County last year, the Merced Police Department said in a statement Saturday. Her statements led police to serve a search warrant at the house in Merced, where her 34-year-old boyfriend Dhante Jackson resides, the …