A co-founder of the fraudulent OneCoin cryptocurrency has been sentenced to serve 20 years in a US prison. Sebastian Karl Greenwood colluded with others, including the so-called "Cryptoqueen" who is now on the FBI's top 10 Most Wanted list, officials say. They are accused of scamming more than $4bn (£3.2bn) from investors. Greenwood, 46, a citizen of the UK and Sweden, was arrested in Thailand in July 2018. He pleaded guilty to wire fraud and money laundering in December. Officials say OneCoin, which was founded in 2014 in Bulgaria, functioned as a global pyramid scheme. Greenwood started and ran the company with Ruja Ignatova, the so-called Cryptoqueen who has not been seen since vanishing in Greece in 2017.