A former top Halliburton executive will serve 2 1/2 years in prison after pleading guilty in Houston federal court to orchestrating a $180 million bribery scheme to secure $6 billion in natural gas deals in Nigeria, the Justice Department announced Thursday.

Albert "Jack" Stanley is the former CEO of KBR, a Halliburton subsidiary at the time of the bribes; he was tapped to run the company in 1998 by future Vice President Dick Cheney, who ran Halliburton between 1996 and 2000. Cheney was not charged in the case.

KBR, spun off by Halliburton in the wake of the scandal, called the scheme an "unfortunate chapter" in its "rich and storied history" after pleading guilty to corporate criminal charges in 2009.

The investigation of the bribes crossed four continents over 10 years and involved five companies in Europe, the U.S., Japan and Nigeria. Criminal and civil penalties in the case have yielded more than $1.7 billion in fines, forfeitures and other sanctions.

"This case shows the importance the department places on putting an end to foreign bribery," Mythili Raman, a prosecutor with the Justice Department's criminal division, said in the Feb. 23 announcement.

Stanley, 69, who also pleaded guilty to mail and wire fraud in a separate kickback scheme, agreed to pay $10.8 million in addition to incarceration. He faced a maximum of seven years in prison, but prosecutors said the lighter sentence was merited by his "substantial cooperation" in the investigation. Stanley had pleaded guilty in September 2008, but his sentencing was delayed 16 times, according to Reuters.

Two co-conspirators in the bribery scheme -- Jeffrey Tesler, 63, a British lawyer, and Wojciech J. Chodan, a salesman for KBR's British subsidiary -- were also sentenced Thursday.

According to the Justice Department, Tesler served as the principal bagman in the scheme, steering more than $180 million in bribes to Nigerian officials between 1994 and 2004 to secure natural gas contracts worth $6 billion. He was ordered to serve 21 months in prison and a pay a $25,000 fine. He had also agreed to forfeit $149 million under the terms of a 2009 plea agreement.

Chodan previously agreed to forfeit $726,000 and was sentenced to one year of probation.

All three men cooperated with authorities in the investigation, the largest multi-company prosecution ever under the Foreign Corrupt Practices Act, a federal anti-bribery statute.

In a statement to U.S. District Judge Keith Ellison, Stanley requested leniency, saying that he had been raised on "traditional American values of hard work, honesty and integrity."

"But somewhere along the way my values were compromised, through ambition, ego or alcoholism," Stanley said, according to Bloomberg.

The U.S. investigation never reached Cheney, despite his leadership role at Halliburton during the time of the scheme. Nigerian officials announced in December 2010 that Cheney would be charged criminally as part of an anti-corruption investigation into the bribes, but those charges were dropped after Halliburton paid a $35 million settlement related to the case.

Under questioning from Judge Ellison, Brad Simon, a lawyer for Tesler, said that bribery remains widespread in Nigeria, one of the world's top oil producers and a key source of imported oil for the U.S.

"It was a fact of life and continues to be a fact of life in Nigeria," Simon said.

