(NBC News) -- On Friday's "Dateline," when police are unable to identify a young murder victim, a dogged investigator employs the help of armchair detectives and new DNA technology to find a killer and the woman's identity.

Here is a preview of Keith Morrison's report:

The obsession, the question that kept them glued to their computers; Who was she, this impossible enigma?

KEVIN LORD: This was a case that was followed online very closely by many people.

She was wearing a pale shirt, the color of lavender. The little details caught the eyes of amateur internet investigators, and one of those armchair detectives took to calling her "Lavender Doe."

And as for what happened next -- remember what we said about obsession?

Watch "Dateline: The Woman with No Name" Friday at 10:15 p.m. on NBC4.