Some years ago, I attended a talk by Ellis Jacob who at the time just published a book on his experiences in Japanese occupied Shanghai ("The Shanghai I Knew: A Foreign Native in Pre-Revolutionary China"). During this talk, in what seemed like an offhand remark, he claimed to have witnessed the assassination of Wang Jingwei while Wang was being chauffeur driven to his Shanghai mansion on Yu Yuen Road by Chinese men.
This struck me as a really important claim. The official narrative from the Imperial Japanese government was that Wang died months later in Japan due to wounds suffered from a previous assassination attempt (before he was made President by the occupying Japanese) and apparently this story remains unchallenged.
How would I, a layman, go about getting this story re-examined and discover if indeed he was assassinated?
Unfortunately, Wang Jingwei was cremated after the war, so you're not going to get any physical evidence from his body. A good start would be to examine the hospital in Nagoya where he died, and examine their old medical records. Presumably it would list his medical procedures and assorted health data.
I have to say I'm rather doubtful of the claim, as googling Ellis Jacob gives his birthyear as 1931, making him no older than 13 at the time of Wang Jingwei's death. And this is the first time I've heard of this claim, although I have heard controversy about whether he died due to a wound or if he was poisoned by the Japanese.