As another ISIS beheading video surfaces this week, all eyes are on the next captive set to undergo the same fate by the Islamic State terrorist organization.

Twenty-six year old Abdul-Rahman Kassig is an American aid worker who was first abducted in October 2013 while administering aid to the war-torn country of Syria. So far, ISIS has released four videos showing the beheadings of two American journalists and two British aid workers, and Friday's video named Kassig as the next victim.

Kassig's family came forward earlier this week with a letter written by their son in June of this year. In the letter, Kassig wrote of his fears while in captivity, along with his continued faith in his newly-converted religion of Islam.

"I am obviously pretty scared to die but the hardest part is not knowing, wondering, hoping, and wondering if I should even hope at all," Kassig wrote. "If I do die, I figure that at least you and I can seek refuge and comfort in knowing that I went out as a result of trying to alleviate suffering and helping those in need."

Abdul-Rahman Kassig was born Peter Kassig in Indianapolis, Indiana. He attended Butler University in 2011 with a major in political science after serving as a U.S. Army Ranger in the Iraq War. Kassig left Butler to return to the Middle East after feeling compelled to offer assistance to those refugees he saw during the war.

"The way I saw it, I didn't have a choice. This is what I was put here to do," Kassig said to CNN's Arwa Damon in a 2012 interview.

Kassig traveled to Lebanon's border hospitals in May of 2012 to volunteer his services for Palestinian refugees fleeing the Syrian conflict. Later that year, he founded the Special Emergency Response and Assistance (SERA) organization to ramp up aid and do more for those refugees. In the summer of 2013, Kassig moved the group's headquarters to Gaziantep, Turkey to better facilitate the food and humanitarian aid routes to the Syrian border. It was during one of these trips deeper into Syria that Kassig was captured on October 1, 2013.

The day after Kassig was named as the next potential target of the Islamic State terrorist group, Kassig's parents, Ed and Paula Kassig, released a heartfelt video pleading with his captors. In it, they explain how their son was inspired at an early age by his grandfather's humanitarian work and how much this work meant to Abdul-Rahman.

"There is so much that's beyond our control," Ed Kassig said in the video. "We've asked our government to change its actions, but like our son, we have no more control over the US government than you have over the breaking of dawn."