I read Anthony Scaduto's book about the Lindbergh baby kidnapping when I was twelve or thirteen. No one person pointed me towards it--although I may have been influenced by having read (oy) Agatha Christie's Murder On The Orient Express.
The book convinced me that Mr. Hauptmann was a Scapegoat. This was the "Crime of the Century," and New Jersey's police, the FBI and all law enforcement agents had to pin it on someone. They found an immigrant who was poor and convenient and ensured he received a pitiful defense. Is anti-German bigotry a form of racism? I don't know; but bigotry is bigotry.
Here is a website which offers many more details:
On an unrelated matter:
my sympathies are with the Providence, RI police who are currently suing the city for wiretapping them in their workplace.