for anybody who wants to know the answer, --- by Ron

probably the easiest way to go here is to remember this as an idiomatic usage of the construction "known to". if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed". as far as i know, these are the only two possible forms.
"known as" is incorrect unless it is followed by a noun:
Albert Einstein made his living as a patent clerk, but he was far better known as the original proponent of the theory of relativity.
--> correct (note that "proponent" is a NOUN)