Was the CEO and producer of Suomi-Filmi 1919-1933 and CEO and producer of Suomen Filmiteollisuus 1933-1935.
Was one of the leaders of bringing "talkies" to Finland. Movies with dialogue were rare in early 1930s, but almost of all of the movies produced after Karu's death have been non-silent ones.
"Father of Finnish cinema" who founded film companies Suomi-Filmi and Suomen Filmiteollisuus, which both produced thousands of hours documentary and feature film material during the years.