The uncle of a 21-month-old boy who was missing for four months in El Salvador says he now will fight to find out why the child's parents were killed in that nation.

"We are left with many questions," Miguel Quintanilla said after arriving in Los Angeles Saturday with the boy, Dennis Orlando Gallardo Quintanilla. Dennis' mother, Lucia Quintanilla, a Salvadoran with U.S. resident status, took her U.S.-born son last summer to El Salvador to be with the boy's father, Jose Ovidio Gallardo. On Oct. 3, the three went for a drive and vanished.

Several days later, the parents were found shot to death on a rural road. There was no sign of the boy. Eventually, an unidentified family friend learned that national guardsmen had been heard arguing over whether to kill the child and one guardsman had said his family wanted the boy.

The family obtained the name of the national guardsman, but Peter Schey, director of the National Center for Immigrants' Rights Inc., maintained the U.S. Embassy did not act on the information promptly. Gregory Lagana, press officer at the U.S. Embassy in San Salvador, said there were good reasons to be cautious--the person holding Dennis "might get scared and try to hide the child."

After the intercession of Sen. Alan Cranston (D-Calif.) and Rep. Julian Dixon (D-Calif.), Schey said, national guard director Gen. Eugenio Vides Casanova called U.S. Consul Fernando Sanchez in San Salvador on Monday and told him, "The child is in my office."