In October 1938, Straffen was referred to a child guidance clinic for stealing and truancy. In June 1939, he first came before a juvenile court for stealing a purse from a girl and was given two years probation. Straffen's probation officer found that he did not understand the difference between right and wrong, or the meaning of probation. The family was living in crowded lodgings at the time, and Straffen's mother had no time to help, so the probation officer took the boy to a psychiatrist. As a result, Straffen was certified as a mental defective under the Mental Deficiency Act 1927. A report was compiled on Straffen in 1940 which gave his I.Q. as 58 and placed his mental age at six.