(CNN) Maybe you've taken a naked selfie for your significant other, or you've let someone take a photo of you in the nude. Once that kind of photo exists, it's all too easy for someone to send or post it without the subject's consent.

That's what appears to have happened to hundreds of female service members, after explicit photos of female Marines and other members of the armed forces were found circulating online last week.

So what can you do if this happens to you?

First, preserve the evidence, says Carrie Goldberg, a New York attorney and a director of the Cyber Civil Rights Initiative , an advocacy group for people whose images were distributed without their consent.

That means: Take screenshots of the posts and relevant Internet search results for your name, and record URLs and messages. Save the information to a computer and print it out, the advocacy group says

Then, consider the following avenues of redress:

Prosecution for this offense specifically

So you could seek prosecution for this specific crime in those states. But you and/or your lawyer should be prepared to be dogged about it.

"Because almost all the laws are so new, law enforcement are still getting the hang of how to apply them," Goldberg said. "At our firm, we have so many cases where (complainants) go to law enforcement and are turned away, even in states that have the criminal law."

Go to the police with your evidence and a copy of the law in your hands, Goldberg said.

"These cases require a great deal of advocacy," she said.

The rules and penalties vary. Some states, like Arizona , require proof that the distributor intended to harm, harass, intimidate or threaten the alleged victim.

But proving the distribution itself is usually no trouble, Goldberg said.

"With the exception of hacking cases, 99% of the time victims know exactly who is responsible, and it's very provable with IP (addresses), login, and other cyber forensic information," she said.

It's a misdemeanor in some states (in Alaska, the penalty is up to 90 days in jail and a fine of up to $2,000), and a felony in others (in Hawaii, up to five years in prison and a fine of up to $10,000).

If you and the perpetrator live in separate states, where should you pursue the case? You could do it in either, but there tends to be less foot-dragging if you take action where the offender lives because her or she is more readily available for arrest, Goldberg said.

Quandaries like these are partly why advocacy groups are pushing for a nationwide law.

"We are calling for legislation that makes it a federal crime to distribute a private, visual depiction of a person's intimate parts, or of a person engaging in sexual conduct, with a disregard for a person's lack of consent to the sharing," the group Not In My Marine Corps said in a statement. The organization was recently started by a female Marine veteran to bring stories of harassment in the service to light.

Prosecution for other crimes

If your state doesn't have a law against this specifically, you might seek prosecution for other, related offenses.

"Often, distribution of images is in the context of greater violence," Goldberg said. "Sometimes the offender not only posts the naked picture but also threatens and stalks in other ways. He may be sending hundreds of text messages or showing up at work, threatening friends and family."

"We see that revenge porn is just one tactic that's used in a greater campaign of abuse," she said.

So preserve the picture evidence to help prosecute a larger harassment case, even in states that don't have laws against nonconsensual porn sharing.

Civil lawsuits

At least 12 states have civil laws that pertain specifically to nonconsensual image sharing. But a victim probably could sue, in all states, for the intentional infliction of emotional distress, Goldberg said.

One high-profile example? A couple of years ago, a New York court ordered rapper 50 Cent to pay more than $5 million to a Florida woman who said he posted a sex tape of her on the Internet in 2009.

Get the material offline

Check out the CCRI's guide to removing material from major online platforms like Twitter, Instagram and Facebook.