DeForest turned out to be somewhat of a charletan. He stumbled onto the control grid quite by accident and never really understood how the triode tube worked, but had the foresight to realise the idea was valuable and acquired the patent. That discovery is what made him famous, but the ideas for several of his later inventions turned out to be stolen from other inventors, including the regenerative detector he stole from Edwin Armstrong.
Armstrong, the inventor of frequency modulation, committed suicide in 1954 in the midst of a legal battle over another of his patents: with RCA over the rights to use FM for television sound.
http://www.leedeforest.org/defendant.html