Hi all -- this story has gotten me hooked on this website and prompted me to finally join! I think the case of "LEK" is so fascinating because it makes you wonder whom amongst your circle may be living a double life, with a new name and fabricated past!
I'm a photographer and have a good eye for comparisons, and have looked at all of the missing persons suggested here. Most of them do not resemble LEK, and the few that share some common features differ enough that I think it would be impossible for any except for one of these missing girls to be her. That would be Kim Mallon, and I am NOT saying that she necessarily was LEK -- only that I think she looks enough like her for it to be a possibility.
Her case does seem to fit the facts, though. Scars from when she was 13 could easily have faded by time she was 50. And I'd be curious to know if the connections between the last name M and some numbers on the infamous note could be more than circumstantial.
Here is a rough chronological side-by-side that I set up. The ridiculously hard lighting and low resolution of the KM photo makes it impossible to compare too accurately, but overall bone structure appears consistent, with a progressively broken (then worked on) nose. It most resembles the one of BST in her 20's, which would be the closest chronologically.
I can also see more similar features between the KM photo and the ones of older LEK, when I look at the differences of expression and lighting in each. For example, look at the wispy peak of hair shared by both on the right side of the forehead. If it's not her, they happen look a lot alike!