"During the period while I was detached temporarily from the Gold Trust and assigned to work in copper mines, I had an opportunity to observe at first hand the actions of Yuri Pyatakov, the vice commissar executed in 1937, after he had confessed to leadership of a wrecking ring. I went to Berlin in the spring of 1931 with a large purchasing commission headed by Pyatakov; my job was to offer technical advice on purchases of mining machinery. Some things happened on that occasion which I never understood until I read Pyatakov's testimony at his trial in 1937."