The other brother said he had not talked to or seen him in twenty years and did not immediately recognize him when he saw his picture on TV.
That would be Bruce Paddock, and it was 10 years. Bruce was probably wise to avoid a long and insightful interview, as are most relatives of mass killers, because of the torrents of abuse that will come their way. What strangers don't understand is that while their only knowledge of psychopathic killers is through their unfortunate acts, their siblings will have different experiences.
To Hitler's mother, Adolf was a mama's boy, caring to a fault, so much so that he allowed his mother's Jewish oncologist to emigrate despite his exterminationist policies vis-a-vis the rest of German Jewry. To his nephew who eventually settled on Long Island, he was the absent-minded uncle who gave him a high post in the German government. This kind of incident is doubly tough on their loved ones because of the abuse from other sources and the loss of a dear relative of whom they only saw the positive side along with the happy memories thereof.
I think these interviews are great, because they provide a portrait of the man that goes beyond Hannibal Lecter caricatures. Paddock is unusual among mass killers in being a resourceful and successful man. It would be interesting to find out what motivated his final actions.