The allegations were first reported by the War Horse and published Saturday through the website Reveal. The author, a Marine veteran and Purple Heart recipient, as well as members of his family, have received numerous death threats since the article was first published. It is unclear how many people are involved in the scandal and how many photos were posted online.

The War Horse’s report focuses on one Facebook group with more than 30,000 members called Marines United. In January, a link to a shared hard drive containing photos of numerous female Marines in various states of undress was posted to the group, according to the War Horse’s report. The hard drive contained images, as well as the names and units of the women pictured. Many of the photos were accompanied by derogatory and harassing comments.

The shared drive has since been taken offline and the Naval Criminal Investigative Service is investigating “incidents related to the Marines United group,” said Capt. Ryan Alvis, a Marine Corps spokesman.

The person who posted the drive was a former Marine working for a defense contractor, said a Marine official who spoke on the condition of anonymity to speak frankly about the photos. The contractor has since been relieved of his duties.