Worldcom's former finance chief has been sentenced to five years in jail for his part in the largest accounting fraud in US corporate history.
Sullivan's sentence is topped only by that of ex-chief Bernie Ebbers
Scott Sullivan played a key role as a "star" prosecution witness in the case against former Worldcom chief Bernie Ebbers who was jailed for 25 years.
The 43-year-old pleaded guilty to conspiracy, securities fraud and making false financial filings.
He co-operated with investigators in the hope of winning a reduced sentence.
'Architect' of fraud
Worldcom collapsed in 2002 following a $11bn (£6.2bn) accounting fraud.
"Mr Sullivan was the architect of the fraud at WorldCom," US District judge Barbara Jones said as she handed down the sentence at the Manhattan court.
WORLDCOM SCANDAL SENTENCES
Bernie Ebbers, former chief - 25 years in jail
Scott Sullivan, former finance chief - five years' prison
David Myers, former controller - one year and a day in jail
Buford Yates, former accounting director - a year and a day in prison
Betty Vinson, accounting manager - five months jail, five months house arrest
Troy Normand, accountant - three years' probation
During the Ebbers trial earlier this year the former finance director said the chief executive had repeatedly ordered him to "hit the numbers" - or adjust the company's accounts to meet Wall Street expectations.
"I told Bernie 'this isn't right'," he told the court as he described a meeting at which he showed Ebbers a plan to fraudulently create $133m in revenues in October 2000.
Ahead of his sentence he told the court: "I am sorry for the hurt that has been caused by my cowardly actions. I truly am ... I stand before you today ashamed and embarrassed."
He also told the court he was "ashamed and embarrassed" of "horrible decisions" he made.
"It was a misguided effort to save the company... I ask for leniency so I can get back to my family as soon as possible."
His testimony was key to illustrating that Ebbers had known about fraudulent accounts entries that covered up spiralling expenses at the company.
Sullivan was recently commended for his help, with prosecutors sending Ms Jones a note saying it was "primarily Sullivan's testimony that contributed to the government's successful prosecution".
Prosecutor David Anders added during the sentencing hearing that without Sullivan's help it was "likely that Mr Ebbers never would have been brought to justice".
Key players sentenced
As well as five years in prison - which are due to begin on 11 November - Sullivan had already agreed to sell an $11m mansion he is currently building in Florida to settle a lawsuit launched by former Worldcom investors.
Four other, lower-ranking, executives involved in the case were sentenced by judge Jones in the past week.
Their punishments ranged from probation to one year in jail as they had also co-operated with prosecutors and pleaded guilty.
However, Ebbers - who was found guilty in March and sentenced last month - has insisted he is innocent and plans to appeal.
Worldcom's collapse was the biggest bankruptcy in US corporate history.
Some 20,000 workers lost their jobs, while shareholders lost about $180bn, when the company filed for bankruptcy protection
The company emerged from bankruptcy in 2004 and is now known as MCI.