Question: Don Barry Mason was the founder of the Psychedelic Shamanistic Institute (PSI), which other member that's Welsh, that died on 10 April 2016?
Related documents: [0]  [DOC] Dennis Howard Marks (13 August 1945 – 10 April 2016) was a Welsh drug smuggler and author who achieved notoriety as an international cannabis smuggler through high-profile court cases. At his peak he claimed to have been smuggling consignments of the drug as large as 30 tons, and was connected with groups as diverse as the CIA, the IRA, MI6, and the Mafia. He was eventually convicted by the American Drug Enforcement Administration and handed a 25-year sentence to be served at Terre Haute; he was released in April 1995 after serving seven years. Though he had up to 43 different aliases, he became known as "Mr Nice" after he bought a passport from convicted murderer Donald Nice. After his release from prison, he published a best-selling autobiography, "Mr Nice", and campaigned publicly for changes in drugs legislation. [END] 
[1]  [DOC] Don 'Barry' Mason (1950–2006) was the founder of the Psychedelic Shamanistic Institute (PSI), a networking organisation that encouraged ethnobotany and scientific research into cannabis and other psychoactive plants while contributing substantially to the public debate about drug policy reform. Associates of PSI include: Mathew Atha, Colin Angus, Brian Barritt, Michael Carmichael, Fraser Clark, Paul Devereux, the late John Entwistle, Paul Flynn MP, Ben Ganly, Lee Harris, Mike Jay, Howard Marks, Dr John Marks, Jonathan Ott, Dr Russell Newcombe, Richard Rudgley and Youth. [END] 
Answer: 
Dennis Howard Marks
Dennis Howard Marks