Hey there Alicia! The link to the article on Findadeath.com is a good one. I heard that in one of the cases, she was killed by the mob because of something that had to do with her restaurant, Thelma Todd's Sidewalk Cafe. You mentioned that you saw Todds in a few pictures on TCM. I'm not sure if you're referring to the ones that she did with Zasu Pitts, which were excellent comedic ones when Hal Roach wanted to make them the female "Laurel and Hardy". Although I haven't written about Todd's mysterious death yet, I did write about Todd's partnership with Pitts if you would like to read it.
[url= http://www.bellaonline.com/articles/art68432.asp]The Partnership of Pitts and Todd[/url]