Peter Kassig beheading is yet another sign of Islamic State brutality. On Sunday, hours after the release of video by the militants claiming they beheaded the former U.S. Army Ranger turned aid worker, Peter Kassig, President Obama has confirmed its authenticity.

It was also in the same day, the Islamic State has released the video showing mass beheadings of Syrian soldiers while at the end of the video, they showed a severed head of a man that they claimed was the former U.S. army ranger.

"Today we offer our prayers and condolences to the parents and family of Abdul-Rahman Kassig, also known to us as Peter," in a statement of Pres. Obama last Sunday. Pres. Obama used the Muslim name of Kassig to indicate ISIS killing of their fellow Muslim.

Peter Kassig beheading destroyed the hearts of his parents Ed and Paula Kassig, but stated that they were proud of their son's devotion to help the Syrian people.

Peter Kassig is a 26-year-old ex-soldier from Indianapolis, after graduation in 2006, he enlisted in the army. After that, he was dismissed from the army due to medical reasons. He volunteered for charity groups assigned in Syria and Lebanon until he was seized by the militants in October 2013.

Peter Kassig converted his name to Abdul-Rahman that means "servant of the most merciful" during his captivity. He is the founder of SERA (Special Emergency Response and Assistance), a humanitarian group.

In the more than 15-minute video released by the ISIS, a group of jihadists in uniform shows the mass beheading of the Syrian military personnel. However, Peter Kassig beheading was not shown in the said video.

 Before the ending of the video, a man with a British accent called as "Jihadi John" by the British media spoke in the video, "To Obama, the dog of Rome. Today we are slaughtering the soldiers of Bashar and tomorrow we will be slaughtering your soldiers," before Peter Kassig beheading was announced in the video.

"This is Peter Edward Kassig, a U.S. citizen ... who fought against the Muslims in Iraq." Jihadi John claimed as he showed a severed head of unrecognized man.

Jihadi John was also the alleged assassin to the two American journalists, James Foley and Steven Sotloff and two British aid workers David Haines and Alan Henning. Peter Kassig beheading is the fifth recorded execution of the ISIS to Westerners.

According to the latest news, Johadi John was one of the casualties during the airstrike coalitions against the ISIS.