Is it illegal to have a picture of someone who doesn't want it?

So this girl has an embarrassing picture of me that she Screenshotted off of one of my friends on snapchat (an app on iphone or android that let's you send pictures to friends for up to 10 seconds) I asked her to delete it and she said no. Would it be illegal to have it in her possession because I don't want her to or not? She's not doing anything with it she just keeps it. I don't know why. She might show it to her friends or something but I don't know. I wanna make her delete it with the law involved so she gets scared and does it.

There's nothing illegal about it. You made it public information or did so indirectly by sending it to a third person. You might have cause to sue her in civil court depending on what she does with it.

You can sue her.

It is not illegal for her to have the photo.

The only time it's illegal for someone to photograph you is when you have an expectation of privacy, such as in the bathroom, in a changing room, in the shower, etc.

If you can be seen, you can be photographed.

- Stuart