"They think I'm crazy," he said softly. "I have to show them that I'm successful before they'll talk to me again."
His middle child, Mauricio, remains devoted. The 27-year-old finance administrator said Nunez was a loving, patient father who came up with his own method to teach Mauricio to read before he went to kindergarten. Now living in Germany, Mauricio said he was sure his dad had developed something significant. But he said Nunez had lost so much to his own invention that he had become paralyzed in the commercialization effort, unsure of whom to trust and fearful of blowing his one shot at redemption.
Even admirers say Nunez's cautiousness is largely to blame for the fact that his cooker is still locked in the lab. American environmental consultant Lilia Abron, who promotes green technology in the developing world, said she could sell plenty of Turbococinas if Nunez would just get them into mass production.
She traveled to El Salvador to view a prototype last year and was thrilled with the stove's efficiency and minimal smoke. She said she urged the inventor to hook up with a major appliance manufacturer to lower the cost, but to no avail.
"The market is there," said an exasperated Abron, a chemical engineer and founder of Washington-based Peer Consultants. "He just won't let it go."
Nunez remains wary. He said he had come up with a natural gas version of the Turbococina that had huge commercial potential. But he has no money for full-scale testing, and prospective partners are asking for too big a share of his invention.
Parr said she wasn't sure if her old friend would ever recoup what he had invested.
"He has lost his wife and his children," she said. "He has paid a really high price."
Times staff writer Alex Renderos contributed to this report.