KING OF PRUSSIA, Pa. — Authorities searched Tuesday for a 10-month-old girl who was declared missing after her grandmother, who was baby-sitting her, was found slain inside the family’s apartment in a Philadelphia suburb.

Investigators are focusing on reuniting Saanvi Venna with her parents in two investigations that are ‘‘intricately connected,’’ said Montgomery County’s district attorney, Risa Vetri Ferman.