There was a Chinese spy in Feinstein’s employ. I would start there.
One of the things that came to light is that in the early 90s, suddenly at least a couple of dozen Chinese attached themselves as fund-raisers and aides to a couple of dozen up-and-coming politicians (and a few established ones). Most of these showed up within about 18 months of one-another.
Charlie Trie, and John Huang weren’t the only ones who managed to tie themselves to successful politicians - but their patronage was a substantial part of getting their clients to the Presidency.