DANBURY, Conn. -- Caroline Ellison, a former top executive in Sam Bankman-Fried ’s fallen FTX cryptocurrency empire, began her two-year prison sentence Thursday for her role in a fraud that cost investors, lenders and customers billions of dollars.

Nishad Singh, former engineering director of the collapsed crypto exchange FTX, has been spared a prison sentence after providing substantial cooperation in the case against FTX founder Sam Bankman-Fried.

Kaplan last month sentenced Caroline Ellison, Bankman-Fried's former girlfriend and an executive at FTX's sister hedge fund Alameda Research, to two years in prison. The judge praised her cooperation, but said that such assistance could not be a "get out of jail free card" in a case as serious as this one.

An ex-FTX executive who testified against the cryptocurrency firm's founder at his trial last year has been spared a prison sentence.

Caroline Ellison, who pleaded guilty to fraud charges tied to the collapse of crypto exchange FTX, is beginning her two-year prison sentence.

Ellison, 30, reported to the federal prison in Danbury, Conn., according to the Federal Bureau of Prisons. She had pleaded guilty and testified extensively against Bankman-Fried, her former boyfriend,