Denis Cuspert, a German rapper who joined the Islamic State (ISIS) group, has likely been killed in an American airstrike in Syria, a defense official said Thursday, according to AFP.

“We believe he was killed in a U.S. strike earlier this month,” the official said, speaking on condition of anonymity.

“He was not considered a high-value target (and) we were not specifically targeting him,” he added, noting that other ISIS jihadists may also have been hit.

Cuspert, who used to rap in Berlin under the name “Deso Dogg”, later went by Abu Talha al-Almani. He was one of the most famous Western fighters for ISIS group, and was already listed as an Al-Qaeda supporter by the United Nations.

Earlier this year, the United States added Cuspert to its list of “terrorists” over his role as a fighter with ISIS, freezing all of his assets under U.S. control and prohibiting transactions with him.

The Islamic State group prohibits music, but singing is allowed. Indeed, some of the jihadists’ grisly videos are set to a vocal sound track.

Jihadist sources in April 2014 said Cuspert had been killed in Syria but they later retracted the claim.

Cuspert joined ISIS jihadists in 2012 and went on to appear in numerous videos from the militant group, including one in November last year “in which he appears holding a severed head he claims belongs to a man executed for opposing ISIL (ISIS),” the State Department has previously said.

Cuspert had pledged an oath of loyalty to ISIS leader Abu Bakr al-Baghdadi and was a chief recruiter of German fighters, officials added.