How do the players discover manshoon and jarlaxles identity?

Is there a way for the players to learn Manshoon’s and Jarlaxles identity? Jarlaxle seems like you just have to catch him in the act and piece it together, but how do you discover Manshoon? Who knows he’s alive? Urstul Floxin? Xoblob? Harpers?Btw I’m on mobile, so sorry. Thanks !