HOUSTON (Reuters) – James Davis, the government’s top witness in convicted swindler Allen Stanford’s fraud trial, was sentenced today to five years in prison for his role in a $7 billion Ponzi scheme. Davis, 64, who pleaded guilty in 2009 to three charges and could have been sentenced to 30 years, told the court in a breaking voice, “I am ashamed and I am embarrassed.” He added that he let down his family, co-workers and thousands of investors.