The German prosecutors, who investigated the scandal after the drug had been taken off the market, concluded in their indictment in 1967 that by early 1961 the executives at Grünenthal (including company owner Hermann Wirtz and Thalidomide-inventor Dr. Heinrich Mückter) had no reason to doubt the damaging effect of Thalidomide any more. They now knew with certainty that Contergan (Thalidomide) was causing nerve damage.
An additional 50 doctors and pharmacists contacted Grünenthal with complaints about nerve damage between December 1960 and February 1961 alone. In January and February 1961, 19 consumers additionally contacted Grünenthal directly to inform them about their own cases of nerve damage.
Grünenthal still did not act.
Source: Anklageschrift (indictment) from 1967, today archived at the National Archives of North Rhine-Westphalia in Duisburg, Germany (Rheinland Division, Gerichte Rep. 139, No. 1–396), p. VII and pp. 132-134.