ABC News October 4, 2014

American Aid Worker, Former Soldier Peter Kassig Threatened in ISIS Video

WATCH: Parents of American ISIS Hostage Make Emotional Plea

American aid worker Peter Kassig is the newest identified hostage of the terror group ISIS, seen threatened in the same video in which a purported ISIS militant murders British captive Alan Henning.

Kassig, 26, is seen at the end of the video that emerged online today, after Henning’s apparent death, as the black clad militant says it is right that ISIS attacks Americans as long as American bomb ISIS targets in Iraq and Syria.

Hours after the video appeared online, Kassig’s family released a statement in which they extended their condolences to the Henning family and “ask[ed] everyone around the world to pray for the Henning family, for our son, and for the release of all innocent people being held hostage in the Middle East and around the globe.”

His parents, Ed and Paula Kassig, also released a video message for him Saturday.

"Know that we love you, and our hearts ache for you to be granted your freedom so we can hug you again and then set you free to continue the life you have chosen, the life of service to those in greatest need," said Paula Kassig. "We implore those who are holding you to show mercy and use their power to let you go."

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A representative of the family released information on Kassig, who they say has taken on the first name Abdul-Rahman. The representative said Kassig is an Army veteran who served in the Iraq war – military records identify him as a former Army Ranger – before he was honorably discharged for medical reasons in 2007.

Kassig later became an emergency medical technician and volunteered as a medical assistant in border hospitals in Lebanon in 2012, treating Palestinian refugees and those fleeing from the Syrian conflict.

In the fall of 2012, the family representative said Kassig founded an NGO called SERA, Special Emergency Response and Assistance, eventually moving its base of operations to Turkey. From there Kassig “sourced and delivered food and medical supplies to the growing [refugee] camps on both sides of the Syrian border.” He also gave primary trauma care to children caught in the crossfire.

Kassig was abducted in October 2013 while traveling to a town in eastern Syria for SERA. For the intervening year, the Kassig family kept silent about his abduction “at the wish of those who have held their son,” the representative said.

ISIS has killed four Western hostages on camera previously: American journalists James Foley and Steven Sotloff, and British aid workers David Haines and Alan Henning.

In a statement released today, President Obama said the U.S. “strongly condemns” Henning’s murder and said his was a “great loss for [the Syrian people], for his family and the people of the United Kingdom.”

“Standing together with our U.K. friends and allies, we will work to bring the perpetrators of Alan’s murder – as well as the murders of Jim Foley, Steven Sotloff and David Haines – to justice,” Obama said.