Dr. Widukund Lenz phoned the head of the scientific department at Grünenthal, Dr. Heinrich Mückter, saying he was highly suspicious that Contergan (Thalidomide), if taken by pregnant women, was responsible for malformations in babies. Dr. Lenz explained to Dr. Mückter why he came to this conclusion and demanded that Grünenthal take Contergan off the market immediately. Mückter refused.
Source: Chronology of events provided by Beate Kirk, in: Der Conterganfall: eine unvermeidbare Arzneimittelkatastrophe? Dissertation. Greifswald 1998.