Scott Sullivan, the WorldCom finance chief, got five years in jail Thursday. He was found guilty in the $11bn fraud that bankrupted the company.
Sullivan, 43, said he was "ashamed and embarrassed" by his actions at the company. "I made horrible decisions," he said. "It was a misguided effort to save the company. Every day I regret what happened at WorldCom and I accept responsibility. I am sorry for the hurt that has been caused by my cowardly decisions. I truly am," he was quoted as saying by Guardian.
Sullivan spent seven days in the witness box earlier this year detailing the fraud at WorldCom. He told jurors that he had repeatedly warned former chief executive Bernard Ebbers accountants were fiddling the books to ensure the company hit its earnings targets.
Ebbers had orchestrated the entire scam with the phrase "hit the numbers". He denied wrongdoing and plans to appeal against his conviction.
Judge Barbara Jones called Sullivan the "architect of the fraud" but cited his "extraordinary co-operation" when handing down the sentence.
Sullivan faced a maximum sentence of 165 years before agreeing last year to plead guilty to three counts of securities fraud and help prosecutors in their pursuit of Ebbers. Prosecutors said his testimony had been crucial in securing the conviction of his former boss on charges of fraud, conspiracy and false filings.
At the sentencing, Judge Barbara Jones described Sullivan as the "architect" of the scheme to defraud investors. "Mr Sullivan's offences were of the highest magnitude," she said.
She said he was granted leniency because of his cooperation and because of his family situation; his wife is diabetic and Sullivan said she had been hospitalised nine times this year alone. The couple have a four-year-old daughter.
The sentencing draws the curtain on the WorldCom saga. Ebbers was sentenced last month to 25 years in prison.