There was a court case in the US where Marconi's essential patents on radio transmission were refuted as everything in them were already patented by Tesla.
Marconi was a student and assistant of Tesla for a time and decided to steal his work and go into business for himself.
Unfortunately this is not widely understood and Marconi is still widely thought to have invented radio when in fact it was Tesla.
The story of Landell_de_Moura is indeed fascinating. Unfortunately there so many technical errors in the reports that they have to be discounted. It is probable that his wireless claims actually refer to light-beam communications..
If any one was first, it had to be David Edward Hughes.
