UPDATE: 11/19/12, 10:00 a.m., EDT. BP has provided additional information on the outside firms that advised it on several other asset sales over the past two years.

BP, the energy giant formerly known as British Petroleum, has agreed to plead guilty to 14 criminal charges and pay $4.5 billion in fines and other payments to the federal government as a result of the 2010 Deepwater Horizon disaster in the Gulf of Mexico, according to sibling publication The National Law Journal.

The settlement adds to the already hefty price tag incurred by BP as a result of the massive offshore oil spill, the second-largest such disaster in history.

Earlier this year, BP announced a $7.8 billion class action settlement with plaintiffs pursing private claims against the London-based integrated oil concern. BP has also agreed to foot a $600 million bill for attorney fees and expenses, and the company has stated publicly it’s already spent about $14 billion cleaning up the spill, as well as another $9 billion from a fund it set up in 2010 to compensate victims.

While lawyers from top Am Law 100 firms like Arnold & Porter, Gibson, Dunn & CrutcherKirkland & Ellis, and Wilmer Cutler Pickering Hale and Dorr took the lead advising BP on the litigation and regulatory front, according to sibling publication The Am Law Litigation Daily, BP also needed corporate counsel to help the energy giant sell off assets to raise the capital necessary to meet its increased spill-related expenditures.

In the aftermath of the Deepwater Horizon disaster, British publication Legal Week reported that BP’s first order of business on the corporate side was hiring Magic Circle firm Freshfields Bruckhaus Deringer for takeover defense work in the event a rival attempted to capitalize on BP’s weakened position by mounting a bid to buy what is now the world’s third-largest energy company.

BP then turned to rival Magic Circle firm Linklaters for counsel in borrowing $5 billion from a consortium of major banks in order to help defray mounting cleanup and compensation costs, according to our previous reports. Linklaters has been a longtime legal adviser to BP, having advised the company on its $110 billion merger with Chicago-based Amoco in 1998 and $27 billion acquisition of La Palma, California–based Atlantic Richfield (Arco) the following year.

The April 20, 2010 explosion of the Deepwater Horizon drilling rig over a wellhead on the BP–operated Macondo Prospect—located about 40 miles off the coast of Louisiana—effectively forced BP to undo some of its past acquisitions. In the ensuing two-and-half years since the spill, which some reports say continues to seep, several outside firms acting as BP’s corporate counsel have helped it raise roughly $35 billion by shedding a variety of assets.

Leading the way is Gardere Wynne Sewell in Texas, which this year advised BP on the $5.6 billion sale of assets in the Gulf of Mexico to Plains Exploration and Production, the $1 billion sale of assets in Wyoming to Linn Energy, and the $227.5 million sale of two natural gas processing plants to Eagle Rock Energy. Gardere also took the lead on BP’s $575.5 million sale of a Colorado gas plant to Anadarko last year and grabbed a role on the company’s $7 billion sale of assets in Canada, Egypt, and the U.S. to Apache in 2010.

The Apache deal was the first major divestiture by BP in the wake of the three-month Gulf of Mexico spill. Other firms working on that transaction included global coordinating counsel Sullivan & Cromwell, Linklaters, CMS Cameron McKenna, and Canadian firm Fraser Milner Casgrain.

FMC, which last week agreed to combine with SNR Denton in a three-way merger, has also been a key legal adviser to BP. The firm represented BP last year on the $1.67 billion sale of its Canadian natural gas liquids business to Plains Midstream Canada, and even grabbed a role on an acquisition—BP’s $7 billion purchase in 2010 of assets in Azerbaijan, Brazil, and the Gulf of Mexico from Devon Energy. (Linklaters and Brazilian firm Barbosa, Mussnich & Arago also advised BP on the Devon deal.)

S&C took the lead for BP in 2010 on the $7.1 billion sale of its stake in an oil and gas joint venture in Argentina to Chinese state-owned CNOOC and Buenos Aires-based Bridas. Another Am Law 100 firm picking up BP transactional work was Morgan, Lewis & Bockius, which advised the company on its $1.9 billion sale of Colombian assets in 2010 and subsequent $680 million sale of Arco Aluminum to a Japanese consortium in 2011.

CMS and British firm Field Fisher Waterhouse handled BP’s $400 million sale of U.K. gas assets earlier this year to Perenco and CMS teamed up in September with Norwegian shop Schodt to advise BP on its $240 million sale of an 18.36 percent stake in the Norwegian Sea’s Draugen field to an affiliate of Royal Dutch Shell.

Linklaters, BP’s longtime go-to M&A adviser, has also represented the company on its $650 million sale of assets in the Gulf of Mexico to Japan’s Marubeni and the $1.8 billion billion sale of assets in Venezuela and Vietnam to TNK-BP in 2010. The Magic Circle firm also handled with Norton Rose BP’s roughly $31.3 million sale of its liquefied natural gas distribution business in the Netherlands to Dublin-based DCC in September.

The Am Law Daily reported last month on Linklaters’s role advising BP on the proposed $17.1 billion sale of its stake in the Russian oil joint venture TNK-BP to Moscow-based Rosneft. (Linklaters, along with associated Indian firm Talwar Thakore & Associates, also took the lead last year on BP’s $7.2 billion purchase of a stake in Indian oil and gas projects with Reliance Industries.)

Other firms that have handled corporate work for BP over the past two years include the aforementioned Freshfields, which advised BP on the $775 million sale of Pakistani properties to Hong Kong-based United Energy Group in 2010, Herbert Smith Freehills, which picked up the work on BP’s $296 million sale in 2010 of fuel marketing businesses in southern Africa to Puma Energy, and DLA Piper, which advised BP in August on the $2.5 billion sale of its legacy Arco business in Southern California to Tesoro. (DLA and Brazilian firm Campos Mello Advogados also advised the TNK-BP joint venture in 2011 on its $1 billion purchase of a 45 percent stake in oil and gas deposits in Brazil’s Amazon basin.)

BP turned to Kirkland and Vinson & Elkins for counsel last month on the sale of its Texas City refinery and a portfolio of related infrastructure to Marathon Petroleum, a deal that, if it reaches its potential value of $2.5 billion, would push the energy giant’s total post-Deepwater Horizon divestitures past the $35 billion mark.

In August, an internal team from BP’s business side handled the company’s $63 million sale of a liquefied petroleum gas business in the U.K. to DCC.

BP’s group general counsel Rupert Bondy had never worked at an oil company until he joined BP in May 2008, according to sibling publication Corporate Counsel. John “Jack” Lynch Jr., who joined BP in 1998, serves as general counsel of BP America, the second-largest producer of oil and gas in the U.S.

Other in-house lawyers at BP who have played key roles in unloading assets for the company over the past two years include associate general counsel Jens Bertelsen, legal counsel for exploration and production Keith Angus, senior attorney for exploration and production W. Brad Bryan, legal manager Brian Selinger, M&A attorney Emily Leung, and managing attorney Jackson Cooley.

On the litigation front, associate general counsel James Neath at BP America in Houston has also played a key role, as has the man who moves BP’s vast funds, group treasurer David Bucknall in London, who was appointed to the role last year following the promotion of predecessor Dev Sanyal to group chief of staff.

BP’s in-house legal department has seen some turnover in recent months.

In September, Steptoe & Johnson hired Foreign Corrupt Practices expert Richard Battaglia, who began his career at BP predecessor Amoco in 1976 and served as senior counsel for regulatory compliance at BP America until December 2011, as senior counsel in its Chicago office. This week, former Freshfields corporate partner Hildegard Bison in Düsseldorf joined BP for a top legal role at its European arm, according to Legal Week.

BP legal chiefs Bondy and Lynch did not immediately respond to requests for comment about the work conducted by the company’s in-house lawyers since 2010 or about how much BP has incurred in oil spill-related legal fees and expenses from its outside counsel over the past two years. A BP spokesman declined to comment.

The $4.5 billion criminal fine being paid as a result of the agreement announced Thursday between BP and the U.S. Department of Justice shatters the previous record set by pharmaceutical giant Pfizer in 2009 when it agreed to pay $1.3 billion to settle false marketing claims involving its Bextra medication. The BP settlement does not resolve civil claims also being pursued by the Justice Department, in which a trial is scheduled to begin in New Orleans next February.

The NLJ reported this month that BP also faces a fight with its former business partners Halliburton and Transocean, each of whom has tried to avoid their own potential pollution liability by blaming BP for the Macondo fiasco.