WASHINGTON – It had to happen: The military’s embarrassing “revenge porn” scandal has expanded to include gay service members. Military investigators have discovered images of soldiers, sailors, airmen and marines — sometimes wearing uniforms on which their nametags are visible; other times engaging in explicit sexual activity — on gay Tumblr pages and other social media sites.

Investigators are unsure how many of the images were shared without the knowledge or permission of the person depicted or how many of the men in the images remain on active duty. A Marines spokesman said at least one man came forward to say he did not agree to have his image posted on the Tumblr page where it was discovered.

The scandal began when a 30,000-strong Facebook group called Marines United was taken offline. MU members shared pictures of female service members naked or engaged in sex. Although initially membership was restricted to U.S. Marines, Fleet Marine Force Corpsman and British Royal Marines, the group eventually expanded to include members from all branches of the service.

Following the closure of Marines United, or MU, members simply formed another group: MU2. When that group, too, was shut down, they formed MU3.

It’s not clear how well organized the group sharing gay military members’ photos is, but those appearing in the images could face action even though they have been victimized. Although gay men may serve openly in the U.S. Armed Forces, exposing themselves or appearing in sexually explicit images while wearing a uniform or parts of a uniform is prohibited by military law. Punishment can include court martial if the service member can be identified.

Military investigators have said they are attempting to identify both male and female victims of the revenge-porn operation using facial-recognition software.