ISIS beheading video: Peter Kassig's family says hearts are 'battered' by son's death

The family of American Peter Kassig, whose severed head was shown in a recent ISIS beheading video, said their "hearts are battered" by the death of the aid worker.

ISIS releaseda video Sunday showing a masked militant standing over the severed head of a man it said was the former U.S. Army Ranger-turned-aid worker, who was seized while delivering relief supplies in Syria last year.

U.S. authorities later confirmed Kassig's death.

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"Our hearts are battered,but they will mend," said PaulaKassig, Peter's mother. "The world is broken but it will be healed in the end. And good will prevail as the one god of many names will prevail."

Kassig, who served in the U.S. Army's75thRanger Regiment, a special operations unit, deployed to Iraq in 2007. After being medically discharged, he returned to the Middle East in 2012 and formed a relief group, Special Emergency Response and Assistance, to aid Syrian refugees.

A certified EMT,Kassighad delivered food and medical supplies and provided trauma care to wounded Syrians before being captured in eastern Syria on Oct. 1, 2013.

PaulaKassigsaid her son had witnessed and experienced firsthand more of the harsh realities of life "than most of us can imagine."

"But rather than letting the darkness overwhelm him, he has chosen to believe in the good in himself and others. Peter's life is evidence that he has been right all along. One person makes a difference."

Peter's father asked that peoplepray this evening at sunset for his son, who reportedly had converted to Islam during his captivity and was going by the nameAbdul-Rahman.

"Pray also for all people in Syria, in Iraq and around the world that are held against their will. And lastly, please allow our small family the time and privacy to mourn, cry, and yes, forgive."

We are not intimidated: Kerry

On Monday, U.S. Secretary of State John Kerrysaid the brutality of the Islamic State group and its
potential spread worldwide was a key reason, among many, that the United States must remain deeply engaged in the Mideast.

ISIS "leaders assume that the world will be too intimidated to oppose them," Kerry said. "But let us be clear: We are not intimidated."

Meanwhile, a father in Wales said on Monday he believes his son, a British medical student, was among a squad of ISISjihadistsfilmed beheading Syrian soldiers in a video posted online on Sunday.

Ahmed Muthana told the Daily Mail newspaper his 20-year-old son Nasser Muthana appeared to be among a group of 16 jihadists who were seen on the video, which also showed the severed head of Kassig.

"I cannot be certain, but it looks like my son," said Ahmed Muthana, who lives in the Welsh capital city of Cardiff.

"He must fear Allah now for killing people. How can he expect to face Allah if he is killing human beings?"

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ISIS includes thousands of foreign combatants and has become a magnet for jihadi volunteers from Europe and North America, Western intelligence agencies have said.

In Washington, the latest ISIS beheading video has the Obama administration scrutinizing how and why the executioners are unhooded and clearly recognizable, CBC's Lyndsay Duncombe reported. Also new was the lack of specific threats about the next hostage who might die only a general threat against the U.S., she said.

"[Defence Secretary] Chuck Hagel said yesterday that they will accelerate the training of Iraqi forces to combat ISIS and that, we know, involves training nine Iraqi security force brigades as well as three pashmerga forces," Duncombe reported.

France's top security official said Monday a Frenchman suspected of joining fighters for ISIS is believed to be among the killers in a video that showed a beheaded American aid worker and a dozen Syrian soldiers.

The British Foreign office declined to comment.

Frenchman seen among beheaders

Interior Minister Bernard Cazeneuve said that there is a "strong presumption" that Frenchman Maxime Hauchard is among the group of Islamic extremist fighters in the video released over the weekend.

Cazeneuve said authorities are analyzing the video and have been investigating Hauchard, who is about 22 and from west of Paris.

French citizens make up the largest contingent of European jihadi fighters who have joined extremists in Syria and Iraq. According to the Paris prosecutor's office, about 1,100 people have been placed under surveillance, and 95 people face charges.