LONDON — Diezani Alison-Madueke was found not guilty of five counts of accepting bribes and one charge of conspiracy to commit bribery at Southwark Crown Court in London. The UK's National Crime Agency investigated her for 13 years.

Doye Agama was acquitted of conspiracy to commit bribery, and Olatimbo Ayinde was found not guilty of bribery and bribery of a foreign public official. Six oil executives were named on the indictment in the case but were not charged.

Alison-Madueke served as Nigeria's oil minister between 2010 and 2015. She was also the first female president of Opec. She joined the Nigerian board of Shell in 2006. The trial began in January.

Defence lawyers argued that documents relevant to the case went missing in Nigeria. They also argued that the delay in bringing the case to court was unjust. The prosecution did not present evidence that Alison-Madueke awarded government contracts to the named oil executives in exchange for bribes.

"At no time did I ask, take, or seek a bribe or bribes of any sort." Alison-Madueke said. She explained that Nigerian ministers are prohibited from holding foreign bank accounts while serving overseas. She testified that she relied on wealthy businessmen to fund her living expenses in London and that they were reimbursed in Nigeria. According to Alison-Madueke, evidence proving these reimbursements was seized from her Abuja home but was not produced by Nigerian authorities.

Former Nigerian president Goodluck Jonathan provided a statement, noting that third parties frequently pay for transport, accommodation, and other expenses for ministers conducting official business overseas. Defence barrister Jonathan Laidlaw KC stated that she was unable to work or travel in the UK for nearly 11 years during the investigation. An investigator from Nigeria's Economic and Financial Crimes Commission testified that Olatimbo Ayinde provided information that assisted the investigation. Ayinde testified that Nigerian security services encouraged her to cooperate with government officials requesting bribes. Defence barrister Jonathan Lennon KC filed a motion to dismiss the case against Ayinde, which the court denied.

"For 11 long, gruelling years this case has hung over my head and has tormented me and my family." Alison-Madueke said in a post-verdict statement. "But today, the past decade of relentless and unjust vilification, condemnation and scrutiny has finally come to an end."

No independent assessment of Diezani Alison-Madueke’s claims was available.