Shell CEO Ben van Beurden picked up the phone and called his chief financial officer hours after Dutch police raided his offices. “I trust you have been informed about what happened at the office,” van Beurden said to CFO Simon Henry on the phone on February 17 last year. “So it looks as if they have some form of coordination between the Italian prosecutor, possibly … with a link into the [U.S. Department of Justice], but we’re not sure yet,” van Beurden said, not knowing authorities were listening in on the other end of the line.

His suspicions were right, and their subsequent conversation sheds light on Shell’s complicity in one of the largest corruption scandals in Big Oil’s history — after the company vigorously denied any role in it for years.

That early morning February raid centered on an oil deal Shell and Italian oil giant Eni struck with Nigeria. They paid the Nigerian government $1.3 billion in 2011 for rights to a giant oil field off the Nigerian coast. After the deal was struck, most of that money mysteriously went missing from public coffers.

New legal filings, emails, and recorded phone conversations reviewed by Foreign Policy showed top Shell executives played a hand in the huge corruption scheme, which reached the highest echelons of the government. The phone recordings and documents from European authorities were obtained by anti-corruption watchdogs Global Witness and Finance Uncovered. Buzzfeed and Italian newspaper Il Sole 24 Or first broke the story.

The new revelations could throw Shell into a world of legal trouble. They also shed light on the shadowy world of oil deals, and how far Shell was willing to go to nab their share of the oil field, known as OPL 245, through a network that spanned former British spies and corrupt Nigerian officials. The tendrils of the scandal reached the highest echelons of the Nigerian government, including former President Goodluck Jonathan.

The latest developments come hot on the heels of the United States repealing an anti-corruption rules for extractive industry companies like Shell, a move Big Oil widely lauded. It also illustrates how resource-rich countries like Nigeria often fall victim to the “resource curse” – where corrupt officials steal the revenue from selling off natural resources, keeping the masses mired in poverty.

One of Africa’s largest petro-states, Nigeria is ranked 136 out of 176 countries in corruption by anti-corruption watchdog Transparency International. Meanwhile, famine spurred by the Boko Haram militant insurgency in the country’s north, threatens millions of Nigerians, including some 500,000 children. The money paid by Shell and Eni for the OPL 245 field is about 1.5 times what the U.N. says is needed to resolve the famine crisis.

The deal centered around former Nigerian oil minister Dan Etete. While serving as oil minister, Etete secretly acquired rights to OPL 245 through a shadowy front company called Malabu, which later funneled over $1 billion of the deal away from the Nigerian people and directly into the pockets of senior Nigerian officials. (Etete was later convicted in a Nigerian court on a separate money laundering probe.)

Van Beurden suspected the Dutch police must have found some dirt in the records their raids obtained. “There was apparently some loose chatter…particularly the people that we hired from MI6 who, er, must have said things like, ‘Well, yeah, you know, I wonder who gets a pay-off here and whatever,’” he said, referring to former British intelligence operatives Shell hired to help navigate the seedy world of West African oil politicking. But it wasn’t just “loose chatter.”

Senior Shell employees openly discussed in email how they knew over $1 billion of their money would go to Etete and others in political kickbacks, according to email records. The company decided to move forward with the deal anyway, denying for years up to this point its employees did anything wrong and claiming it only knew it was paying the Nigerian government.

One email from Shell official Guy Colegate to colleagues in March, 2010 sums it up: “Etete can smell the money,” Colegate wrote. “If, at nearly 70 years old he does turn his nose up at 1.2 bill he is completely certifiable…but I think he knows its [sic] his for the taking. I don’t think he will push it away,” he wrote. That email was forwarded to then-Shell CEO Peter Voser, one of the world’s most powerful oil execs at the time. No records available show he informed authorities or stood in the way of the deal.