THE family of a 32-year-old beaten to death with hammers in St Louis are struggling to understand why he was killed.

Bosnian immigrant Zemir Begic was allegedly murdered by a gang of teenagers in front of his fiancee.

The couple were driving through the Missouri city at around 1.15am with another male passenger when five youths started hitting the vehicle with a hammer, police said.

Mr Begic got out of the car and the group then allegedly hit him in the mouth, head, face and body. He later died at a nearby hospital.

His relatives are preparing for his funeral today in Iowa as detectives try to uncover the reason for his death, Fox News reported.

Robert Joseph Mitchell, 17, has been charged with first-degree murder, while two other suspects, aged 15 and 16, remain in custody. A fourth suspect is still at large.

Mr Begic was allegedly “taunted” and “challenged to a fight” in front of his fiancee Arijana Mujkanovic, the police report said.

No motive has been identified, but members of the close-knit Bosnian community are questioning whether Mr Begic’s death and other recent crimes in the neighbourhood were racially charged.

Mr Begic was white, while Mitchell and one of the two juveniles are black, and the other is Hispanic.

Hundreds of protesters rallied over his death this week, embracing similar tactics to the Ferguson protesters.

Their shouts of “Bosnian lives matter” echoed the “Black lives matter” chant heard around the US following the fatal shooting of unarmed teenager Michael Brown by a white St Louis police officer in August.

Mr Begic’s death has invoked the spectre of ethnic cleansing in former Yugoslavia, which led around 70,000 Bosnians to settle in the US over the past two decades.

Dzevada Keranovic, secretary for United Bosnian Association, told KTVI-TV: “A lot of people are disappointed with the police, with the local government, they think they are not doing enough.

“They believe the teenagers were just all hyped up because of everything going on with Ferguson and feeling injustice or whatever and they just grabbed the first person.”

But St Louis Mayor Francis Slay rejected the idea of a racial motivation in Mr Begic’s death, saying: “Speculation that this attack had anything to do with the Ferguson protests is absolutely unfounded.”

Police chief Sam Dotson also denied a racial link, while vowing to bring a stronger police presence to the streets of St Louis.

But Seldin Dzananovic, a 24-year-old Bosnian, claims he was attacked by teenagers with hammers in the same neighborhood about an hour before Mr Begic, but only suffered minor cuts and bruises.

A resident of the Bevo Mill neighbourhood, known as “Little Bosnia”, told Fox News that he and his family had experienced a similar attack, claiming that there is a disturbing pattern of violence against white Bosnians in the area.

Zemir’s younger brother Rasim said he would not rule out the possibility the murder was racially motivated, saying he wants police “to investigate everything”.

“All we want is justice for Zemir,” said the 20-year-old pre-med student at the University of South Dakota. “He was my role model. He would have given you the clothes off his back.”