A Marine has pleaded guilty at a summary court-martial to sharing explicit pictures on the Marines United Facebook group without permission and will be administratively separated, the Marine Corps announced on Monday.

After pleading guilty on June 29, the Marine was sentenced to 10 days' confinement, reduction in rank by three grades and forfeiture of two-thirds of one month's pay, according to a Marine Corps News release on Monday, which did not include the Marine's name, rank or unit.

"Summary-court martial proceedings are considered administrative in nature, and so the identity of the Marine is not releasable per the Privacy Act," Corps spokesman Maj. Brian Block told Marine Corps Times.

In March, Marine veteran Thomas Brennan first reported for The War Horse that active-duty Marines were among the 30,000 members of the Marines United Facebook group, who were sharing nude photos of female service members and other women, making degrading comments about the women and going so far as threatening some of the women photographed.

Since then, two other Marines have been administratively separated, seven received non-judicial punishment and 22 received adverse administrative actions, according to Monday's news release. 

"These cases span beyond the Marines United Facebook page and include a spectrum of behavior," the news release says. "While many cases involve photos, clothed or explicit, some involve verbal remarks without images. "

Last month, Sen. Kirsten Gillibrand, D-N.Y., told Marine Commandant Robert Neller that she was underwhelmed by the small number of cases that had been referred to court-martial.

"You know which photos are posted; you know where they came from; there are evidentiary trails to be made," Gillibrand said at a June 15 Senate Armed Services Committee hearing. "So I wouldn't say that it's likely that these are cases where they couldn't prove their case. I think it sends the wrong message. If you're not taking these crimes seriously as an enormous disruption of good order and discipline, I fear that it's not going to change behavior."