ST. LOUIS • One teen was charged with murder, two more were held and a fourth was sought Monday as officials spent another day trying to quell speculation that the bludgeoning death of a Bosnian immigrant was racially motivated.

“There is no evidence that this was a crime occasioned by the race or ethnicity of the victim,” Mayor Francis Slay declared in a formal statement. He added, “Speculation that this attack had anything to do with the Ferguson protests is absolutely unfounded.”

Police have been saying the same thing about the killing of Zemir Begic, 32, who was beaten to death with at least two hammers near Gravois Avenue and Itaska Street about 1:15 a.m. Sunday.

Robert Joseph Mitchell, 17, who lives on Winnebago Street, turned himself in at city police headquarters late Sunday and was charged with first-degree murder and armed criminal action. It was unclear whether two other suspects in custody, juveniles 15 and 16, will be charged as adults. Police said they know the identity of a fourth participant, who is sought.

Mitchell and one of the two juveniles in custody are black, police said; the other is Hispanic.