One of the Islamic State’s most prominent decapitators, allegedly responsible for beheading more than 100 people, has been stabbed to death in the outskirts of northern Iraq’s city of Mosul, reports Iraqi News, citing the Arabic-language al-Sumaria News.

“An unknown armed group killed on Sunday the Islamic State’s most famous decapitator, the so-nicknamed ‘Abu Sayyaf,’” a source reportedly told al-Sumaria News, adding, “The armed group ambushed him at al-Dawasa region, in the western side of the [Nineveh] city, and stabbed him several times. He died immediately.”

Abu Sayyaf — which reportedly means to “bearer of the sword” in Arabic and is also the name for the ISIS Filipino branch — is described by various news outlets as ISIS’s top decapitator in northern Iraq’s Nineveh province, where the cities of Nineveh and Mosul are located.

The ISIS branch in the Philippines is renowned for its kidnappings for ransom, bombings, ambushes of security personnel, public beheadings, assassinations, and extortion.

“He had beheaded 100 of violators of the group’s rule” and dumped the severed heads “at a well-known hole in [the] al-Khasafa region,” said the al-Sumaria News source, referring to the decapitator.

“Abu Sayyaf was one of the scariest executioners in Nineveh. He was known for his huge body and heavy arms. He was one of the renowned faces in the ISIS propaganda videos,” Muhammad Yawar, an Iraqi journalist, told ARA News, adding, “Abu Sayyaf was a reflection of the brutality of this terrorist group.”

Many top ISIS leaders have been executed since the Iraqi government launched a U.S.-backed offensive to retake Mosul, Iraq’s second-largest city and ISIS’s last major stronghold in the country, in mid-October.

Iraqi Lt. Gen. Abdul Ghani al-Assad told Reuters earlier this month that the majority of ISIS commanders in eastern Mosul have been killed.

The U.S.-backed Iraqi alliance, primarily made up of tens of thousands of government security forces, Kurdish Peshmerga troops, and Iran-allied Shiite militias, recently liberated the eastern side of Mosul.

However, USA Today reports that “an estimated 750,000 civilians trapped in western Mosul by the Islamic State are facing beatings, executions, starvation and forced military conscription of children as they wait desperately for Iraqi troops to free them.”

ISIS is notorious for barbaric executions of its opponents and even its own members who violate its extreme religious views.

The jihadist group has committed genocide against various ethnoreligious minority groups in Iraq and Syria, primarily Yazidis and Christians.