A Washington Post investigation has found solid evidence that Elon Musk did not have the legal right to work in the U.S. when he ditched graduate school and began a start-up company. Some of The Post's findings: Musk arrived in Palo Alto in 1995 for a graduate degree program at Stanford University but never enrolled in courses, working instead on his start-up. Leaving school left Musk without a legal basis to remain in the United States, according to legal experts. Foreign students cannot drop out of school to build a company, even if they are not immediately getting paid, said Leon Fresco, a former Justice Department immigration litigator. The start-up was called Zip2.