What to Know About the New ‘Jihadi John’

British-Indian Siddhartha Dhar is now believed to be the masked executioner who is depicted killing five hostages in a new ISIS video, after the BBC cited an unnamed official saying that Dhar, who goes by the nom de guerre Abu Rumaysah, is the focus of a probe into the video.

This has led some to dub him the new “Jihadi John,” the same nickname given to the British-born ISIS executioner later identified as Mohammed Emwazi, who is believed to have been killed in an air strike late last year.

Here’s what you need to know about the person alleged to be the new man behind the mask.

Who is he?
Dhar, who was known as “Sid” to friends, enjoyed drinking, loved the bands Nirvana and Linkin Park, and had dreams of becoming a dentist, the Daily Mail reports, citing interviews with his family. After his father died when he was 16, Dhar, who is from London, dropped out of school and later became a bounce-house salesman. He reportedly converted Islam in his late teen years and eventually joined the banned radical group al-Muhajiroun. He married his wife Aisha Tariq, and went on to have five children with her.

What did he do after becoming radicalized?
Dhar went on to become a prolific figure among radical Islamists in London, frequently attending demonstrations against the U.S., Israel, Arab regimes or any other cause the group believed to be un-Islamic, the BBC reports. He was also known to stand outside mosques on Friday afternoons with the aim of recruiting new followers to al-Muhajiroun’s radical way of thinking. Dhar, who is now believed to be 32, has spoken openly about his extremist views to the BBC, CBS News and Vice prior to fleeing the U.K. During a BBC debate on why British Muslims were joining ISIS, Dhar said: “For 90 years we have been without a caliphate and many of the rules within the Koran cannot be implemented … As a Muslim I would like to see the U.K. governed by the Shari‘a. It is far superior to democracy. I don’t really identify myself with British values. I am Muslim first, second and last.”

What led him to ISIS?
Dhar was arrested in September 2014 alongside radical preacher Anjem Choudary for encouraging terrorism and supporting the banned group al-Muhajiroun. Just hours after he was granted bail, the Telegraph reports, Dhar caught a bus to Paris with his family and then traveled into Syria, where he joined the Islamic State of Iraq and Greater Syria. He boasted of his escape, on a Twitter account that has since been suspended, by posting a photo of himself, purportedly taken in Syria, of him holding a rifle while cradling his newborn son. “What a shoddy security system Britain must have to allow me to breeze through Europe to the Islamic State,” he wrote in the tweet.

Is he definitely the man in the video?
His family doesn’t think so. Upon hearing the audio of ISIS’s latest video, his sister Konika Dhar told the BBC that she feared the masked murderer was her brother. “I was in a state of shock,” she said. “I believed the audio to resemble, from what I remember, the voice of my brother but having viewed the short clip in detail, I wasn’t entirely convinced which put me at ease.” Konikha, who lived in London, later told the Press Association: “I examined the features — one eye is smaller than the other, my brother has symmetrical eyes. The eyebrows are bushy and this guy is taller, my brother is shorter and he has got broader shoulders, but he has got stooped shoulders so I don’t think it is.” She said she would “kill him” if the masked executioner was indeed him.