The mother of American photojournalist James Foley—reportedly the subject of a brutal beheading video released today by the militant group ISIS—spoke out Tuesday night to praise her son and request mercy for the remaining hostages.

Foley's mother, Diane, posted the message on the "Free James Foley" Facebook page around 9:30 pm.

We have never been prouder of our son Jim. He gave his life trying to expose the world to the suffering of the Syrian people.

We implore the kidnappers to spare the lives of the remaining hostages. Like Jim, they are innocents. They have no control over American government policy in Iraq, Syria or anywhere in the world.

We thank Jim for all the joy he gave us. He was an extraordinary son, brother, journalist and person. Please respect our privacy in the days ahead as we mourn and cherish Jim.

US officials have not yet confirmed the authenticity of the video.

A National Security Council spokeswoman said in a statement that, "The intelligence community is working as quickly as possible to determine its authenticity. If genuine, we are appalled by the brutal murder of an innocent American journalist and we express our deepest condolences to his family and friends. We will provide more information when it is available."

[image via AP]