(NBC NEWS) – Tonight on “Dateline,” police are perplexed when they find the body of a young woman but aren’t able to identify her.

When the case gets the attention of amateur internet investigators, they begin referring to the mystery woman as “Lavender Doe,” a reference to the distinctive color shirt she was found wearing.

With the help of amateur internet investigators and new DNA technology, a dogged investigator finds her killer – and her identity.

Here’s a preview of Keith Morrison’s report:

Eleven years after the murder of the young woman they called “Lavender Doe,” and more than two hundred miles from the spot where her body was found, in the town of Killeen, Texas — a man was feverishly at work.

It wasn’t his profession, this work that consumed him. Not yet at least.

KEVIN LORD: I kind of spent a lot of my time looking into missing persons’ cases really just trying to flesh out the stories of some of these lesser-known cases.

His name is Kevin Lord. He is, well, many things. A former software developer, a t-shirt salesman, a passionate and loyal consumer of all things true crime.

He wasn’t an investigator — or a law enforcement officer.  Just someone plagued by unanswered questions.

KEVIN LORD: I was looking for Jane Does in the area in Texas that might be a match to one of these missing girls.

And that’s how he came across hundreds of pages of online forums — about a mystery woman nicknamed, “Lavender Doe.”

Could she be one of the missing women he was trying to locate?

Watch “Dateline” Thursday’s “The Woman With No Name” right here at 10 p.m.