Bernie Ebbers, former head of US telecoms giant WorldCom, has been jailed for 25 years on seven counts of filing false documents.
The 63 year-old is the first of six WorldCom executives to be charged over the collapse of the company, which left 20,000 workers jobless and cost shareholders about $180bn.
Judge Barbara Jones said that Ebbers "was clearly a leader of criminal activity in this case. A sentence of anything less would not reflect the seriousness of the crime."
She acknowledged that given Ebbers's age the sentence would probably be for life.
Ebbers bought WilTel Network Services and renamed it WorldCom in 1995. Shares peaked in 1999 at the height of the dotcom bubble and Bill Clinton called him " the embodiment of what I want for the future".
However, Ebbers was forced to resign in 2002 when it was revealed that he had borrowed money from the company. Later that year WorldCom folded after a series of accounting frauds.
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