Germany has launched a probe into who leaked the arrest warrant for an Iraqi murder suspect to far-right groups in Saxony's eastern city of Chemnitz.
A fatal stabbing of a 35-year-old German-Cuban man on Sunday sparked days of violent and xenophobic protests.
The unauthorised disclosure has increased concerns of possible links between police and anti-migrant groups.
Meanwhile, local authorities called on the help of federal police, as they brace for fresh protests on Thursday.
Police have also opened 10 cases against far-right protesters who gave the illegal Hitler salute during the first day of unrest.
A state official called the arrest warrant leak - most likely from a police or judicial source - a scandal.
"We have a bigger problem to deal with there," said Martin Dulig, the state of Saxony's deputy premier, to German media.
The disclosure - which led to the warrant being published on far-right websites - is highly unusual in Germany, which has strict rules for judicial proceedings.
Critics believe the warrant, with details of the number of stab wounds, may have been leaked to further incite anti-immigrant sentiments.
What happened on Sunday?
In the early hours, a fight broke out between "multiple nationalities" on the sidelines of a street festival, police said.
The stabbing victim, a 35-year-old carpenter named Daniel H, was critically wounded and died in hospital.
It remains unclear what triggered the brawl, but police dismissed online rumours that the victim had been defending a woman from sexual assault.
Two other German men with him, aged 33 and 38, were seriously hurt, police said.
A 22-year-old Iraqi man and 23-year-old Syrian were arrested and charged with manslaughter on Monday.
A half-Cuban woman who grew up with Daniel H, Nancy Larssen, told Deutsche Welle news that media misreporting had helped fuel the "horrible" far-right protest.
Another friend of Daniel H, quoted by the Chemnitz news site Freie Presse, described him as left-wing, with a seven-year-old son.