Unfortunately there likely won't be a shortage of connections. Let's face it, depraved men intent on harming beautiful women will go to sites where they can find them. However, that doesn't mean that their deaths were related to their MM profiles/postings.
Here are a few more that I've seen where MM has been mentioned:
Kayla Croft-Payne. Missing Apr 20/10 from Napavine WA. She apparently told someone that she was 'off to a model shoot'. They found Model Mayhem on her computer. (Connection to MM may have been debunked...
http://hometowndebate.com/detectives-exhaust-two-leads-in-recent-search-for-kayla-croft-payne-cms-933 )
Lisa Renee Davis - went missing in 2009 from TN. (While Lisa had MM profile, I don't think it was associated with her murder.
http://www.foxnews.com/story/2009/03/13/details-emerge-about-tennessee-model-slain-in-mysterious-murder/ )
Robyn Garner, from Maryland, went missing in Aruba. She was traveling with Gary Giodano. Robyn had a profile on MM I believe.
Christiana Fesmire, from Maine. July 1/11. While Christiana has been named in the past as having a profile on MM, she was an escort and her madam's brother was convicted of her murder.
And, the notorious Luka Magnotta. Luka was a pornographic gay model who was also a sadistic killer. He had a profile on Model Mayhem. He killed and dismembered his victim, posted the video online, and mailed body parts to different recipients in Canada (May 2012). He was also known to post videos of torturing/killing kittens online. (Such a sweet guy!!)
These are the links to deadly crimes that I've come across so far.