Ground penetrating radar and police dogs have indicated the spot where roger dale Madison's remains are believed to be located.
Road construction worker Mack Ray Edwards confessed to murdering the boy and throwing him down a hole in 1968 as the 23-freeway was being built.
However, the confession fell through the cracks for decades until a writer began researching the case.
Edwards, who is known as the most notorious serial killer of children in California history, admitted that he had killed six boys and girls over a 15-year period.
Edwards committed suicide while on death row at San Quentin prison in 1971.