How can I find out the identity of a person with just a photograph

Is she someone you met online? from Ghana or Nigeria or Russia? Is she asking you for money?

It is not going to happen, if you put them into Facebook they may hit with someone but the only people that have facial ID is the government, and it requires a data base of photos to compare to.

So why do you need to ID them, a witness to a crime? Where are they from? How do you possess the photo?

Like Chuck said, no way for you to do it.

Here's a funny thing about pictures nowadays. I could start a Facebook profile with a picture of Julia Roberts, change the name to mine, or someone else's, and voilà, now, whenever someone uses a picture recognition program online, my name will show up. But I'm not Julia Roberts. I wish! But I'm not.

I could start multiple Facebook profiles with different people's photos, and if a person had that specific photo (it would have to be that specific photo), and found the right site to scan it and find out who's in that picture (and that site would have to have that specific picture in their database), that picture would show up as me, even thought it's not me.

So really, there's no way to find out the real identity of someone based on just a picture.

I had a Facebook stalker (scammer) a few weeks ago. They set up about 10 fake Facebook pages with either my photo, or photos of friends, trying to friend, or contact people I knew.

A percentage of online dating sites, people use fake photos, esp if they are just looking for online sex talk or photos of other people, also in scams, people almost always use fake ID, fake photos and more.