Might know/ might knew

Hi,



Which one of the following three sentences is more accurate? I used #1 in a conversation, but I was not sure about it. I thought ‘knew’ to be more appropriate because I was telling the other person what I thought at the instant when I read the news.



1. When I read the news, I thought you might knew about it.



2. When I read the news, I thought you might know about it.



3. When I read the news, I thought you might have known about it.



Thanks,



MG.