Douglas McArthur McCain, the American citizen killed while fighting for the Islamic State in Syria, was once a fun-loving, bastketball-playing amateur rapper, it has emerged.

Although details are still emerging about McCain, who was killed by members of the Free Syrian Army over the weekend of 23-24 August, news teams and former friends have already begun piecing his back-story together.

Their accounts tell us that the FSA fighters found $800 in cash, and a US passport, on McCain's body after their cut him down. His death comes two months after 15 Somali-Americans from Minnesota were believed to have linked up with Isis in Syria.

McCain was active on social media, where he went by the name "Duale Khalid" on Twitter and "Duale ThaslaveofAllah" on Facebook. His Twitter bio reads "It's Islam over everything," and a tweet from 14 May proudly claims he "reverted to Islam to 10 years ago" and called it "the best thing that ever happen [sic] to me."

On 26 June, he retweeted a tweet that in part said "pray for ISIS."

McCain's Facebook bio says he was born in Chicago, lived in San Diego and studied at San Diego City College. NBC News said he moved from Chicago to Minnesota before moving again to California after high school.

Those who knew McCain said he was an aspiring rapper, and a happy presence at school - hardly the sort of character one would normally associate with militant jihadism. Classmates from Robbbinsdale Cooper High School in New Hope, Minnesota, said he was "always smiling" and liked to joke and play basketball.

"He was a goofball in high school," according to an unnamed classmate. "Doug was a fun guy to be around. Played basketball, joked a lot, had a small sense of humor. Got along with most ... Wasn't the best athlete, but liked to play."

McCain was desperate to be recognised for his rapping; he even went to Sweden to enter a rap battle. Kevin Törnström Kohlin, one of the Swedes McCain met on the trip, said he talked about religion with McCain and "he respected my Christianity."

While in California, McCain worked at African Spice, a Somali restaurant, and frequented a San Diego mosque.

"He was a normal guy, who was social, open-minded, liked to smile always, and always wanted to be a good Muslim," said an unnamed acquaintance of McCain's from African Spice.

It's unclear exactly when McCain joined Isis, but in April, he traveled to Turkey, a frequent way station for people on the way to fight in Syria.