Captive John Ridsdel was beheaded last month after the Canadian government refused to pay a ransom for his release.
Vince Li was found not criminally responsible for beheading a passenger on a Greyhound bus in Manitoba in 2008. He was admitted to a psychiatric hospital and has been living in a group home for about a year.
A monitoring group says the militants committed a mass kidnapping after attacking areas held by the Assad regime in the province of Deir al-Zor.
The militant group released a video that purportedly shows the beheading of four Kurdish Peshmerga fighters in retaliation for the raid that freed 70 prisoners last week in Iraq.
The militant group released footage that purportedly shows a Nigerian soldier being decapitated on the same day that coordinated explosions killed 37 people.
An online image circulated Wednesday purported to show a Croatian hostage held by the Islamic State group's Egyptian affiliate having been beheaded.
The militants beheaded two woman and one of their husbands in Syria during the past week — reportedly the first time they have beheaded civilian females.
The man accused of decapitating his boss and causing an explosion last Friday near Lyon reportedly told investigators he "wanted to commit suicide as part of a media stunt."
The militant group this week also released gruesome photos and video of the executions of captives by drowning, rocket launcher, and beheading.
After 21 Christian Egyptians were apparently beheaded in a video released by the Islamic State on Sunday, Egypt today struck back with airstrikes on the group in Libya.
Many Muslim leaders, even within militant ranks, have condemned the burning execution of Lt. Muath al-Kasaesbeh, saying the act goes against Islamic principles.
A video released Saturday appears to show the masked militant known as "Jihadi John" executing Kenji Goto, a Japanese journalist kidnapped in Syria.