Goldman Sachs helped the fund, 1Malaysia Development Berhad, commonly known as 1MDB, sell more than $6 billion of debt to investors, ostensibly for projects that would benefit the Malaysian people. But federal prosecutors contend that at least $2.7 billion of that money went to fuel the lavish lifestyles of several people close to a former Malaysian prime minister, including the flamboyant financier Jho Low.