A 60-year-old retired Tustin man who shot his mother and his two foster children as they slept has died from a self-inflicted gun-shot wound, authorities said. Leon E. Huffman told police by phone that he had shot the three and was going to kill himself. Police said Huffman left a note explaining that he was distraught over a heart ailment. He left detailed instructions to help his wife, Betty, put the family’s affairs in order. Huffman’s mother, Alice, 86, was killed as were William Barr, 11, and Frankie Balisterire, 8.