Salem bin Laden is the oldest son of Mohammed bin Laden, and brother of Osama bin Laden. He took over his father's estate and construction business in 1972. In 1977 he invested in George W. Bush's new oil company, Arbusto Energy.
He died in a 'freak accident' in 1988, when his ultralight aircraft crashed into power lines near San Antonio. He was a very experienced pilot with 15,000 hours of experience.
Sources:
http://www.americanfreepress.net/10_07_01/Bush___Bin_Laden_-_George_W__B/bush___bin_laden_-_george_w__b.html