, it tends to speculation , conspiracy theories or , at best , circumstantial evidence 
(ROOT (S (, ,) (NP (PRP it)) (VP (VBZ tends) (PP (IN to) (NP (NP (NN speculation)) (, ,) (NP (NN conspiracy) (NNS theories)) (CC or) (, ,) (ADVP (IN at) (JJS best)) (, ,) (NP (JJ circumstantial) (NN evidence)))))))
(ROOT (S (, ) (NP (PRP )) (VP (VBZ ) (PP (IN ) (NP (NP (NN )) (, ) (NP (NN ) (NNS )) (CC ) (, ) (ADVP (IN ) (JJS )) (, ) (NP (JJ ) (NN )))))))