The alleged rape of a 13-year-old Russian-speaking girl in Berlin, supposedly by asylum-seekers, has fuelled anti-migrant protests from Germany's large Russian community.
But the outrage was sparked by Russia's media propaganda machine. And now the Kremlin is stepping in.
Thousands of Russian-speakers took to the streets across Germany at the weekend protesting against what they say is a cover-up by police.
"Our children are in danger," read one banner. "Hands off my child," read another.
Seven-hundred protesters gathered outside Angela Merkel's chancellery on Saturday and other demonstrations have been held outside asylum-seekers' homes in Berlin and Southern Germany.
More on Germany's response to the refugee crisis
The demonstrators were angry after reports on the popular Russian television station Channel One that a 13-year-old girl from a Russian-immigrant family had been abducted on her way to school and gang-raped by "southern-looking" asylum-seekers.
But German police say that after questioning and examination it was clear that Lisa F was not abducted and not raped. Sexual contact was not forced, say officers. Because the girl is only 13 years old prosecutors are investigating two men for child abuse.
The age of consent in Germany is 14 and while sex with an under-aged child is classed as statutory rape, it is generally seen as child abuse if violence was not used.
Social media outrage
On 11 January Lisa F was reported missing by her family. She re-appeared the next day.
But a TV interview given by a woman identified as the girl's aunt claimed that the girl was raped by numerous men over the 30-hour period while she was missing. The report that sparked the protests was spread on social media and has so far been watched more than a million times on Facebook.
German lawyer Martin Luithle has now reported the Russian journalist behind the report, Ivan Blagoy, to the police for incitement.
The case has been taken up enthusiastically by right-wing extremists in a bid to fuel anti-migrant sentiment.
Germany took in 1.1 million refugees and migrants in 2015 and migration is an explosive issue. The far-right NPD and the Berlin branch of the anti-Islam Pegida movement have helped organise the protests.
Links between Russia and far-right groups in Germany are not unusual.
Russian flags and symbols are often seen at anti-Muslim Pegida protests. And the Berlin district of Marzahn, where Lisa F's family lives, is heavily populated with Russian-speakers, and is notorious for xenophobic right-wing extremist protests.
But now the case could be turning into a diplomatic row between Germany and Russia, as the Kremlin gets involved.
"It's clear that the girl did not disappear voluntarily for 30 hours," Russia's Foreign Minister Sergei Lavrov said during a news conference in Moscow on Tuesday, accusing German officials of a politically-motivated cover up.
"I hope that these problems are not swept under the carpet and that there'll be no repeat cases like that of our Lisa."
In fact Mr Lavrov had been asked about German-Russian relations. But by opting to talk so bluntly about what's become known as the "Lisa case," Mr Lavrov is clearly calling into question Germany's authorities.
These allegations are particularly potent since the debacle in Cologne, when police failed to protect women from sexual assaults on New Year's Eve.
Berlin's Interior Minister Frank Henkel has responded by saying he is baffled by Moscow's involvement in an ongoing police investigation, countering that German police and prosecutors abide by the law.
"The accusation that investigators are covering something up does not become more correct, simply by continually repeating it," he said.
Other German politicians, from across the political spectrum, have expressed outrage, accusing Moscow of inflaming far-right conspiracy theories in Germany.
- German Foreign Minister Frank-Walter Steinmeier was adamant there was no justification to use the case "for political propaganda, and to inflame and influence what is already a difficult debate about migration within Germany".
- Chancellor Angela Merkel's spokesman, Steffen Seibert, said the authorities should be allowed to investigate without external intrusion. "There is no reason, in fact it is even impermissible, to make political use of this case," he said.
- The chair of the German government's foreign affairs committee, Norbert Roettgen, complained that "manipulation and untruths are common methods in the propaganda used by the Russian leadership. The case shows that domestic questions of power in Russia appear to be more important than relations with other countries."
But some German commentators have criticised the Berlin police force for poor communication.
Although investigators are pursuing charges of child abuse, critics say it was not clear from initial police announcements that the case was being followed up.
This initial lack of clarity played into the hands of anti-migrant activists hoping to inflame tensions.
Kremlin-backed media have often been accused of using propaganda to stir up trouble with Russian-speakers living in the Baltics.
But now some fear the same tactic could be being used in Germany, possibly to keep Chancellor Angela Merkel on the back-foot when it comes to the fate of EU sanctions imposed on Russia because of the conflict in eastern Ukraine.
Germany's New Year's Eve sex attacks
- More than 1,000 offences, including 384 sex attacks, reported mainly on New Year's Eve in North Rhine-Westphalia
- Majority in Cologne but also Duesseldorf and Bielefeld
- In Hamburg, 195 offences were reported, most were sexual assaults
- Cases also reported in Baden-Wuerttemberg, Nuremberg, Munich and other cities
- Few suspects identified, most attackers described as of Tunisian, Moroccan and Algerian origin
From BKA police report cited by German media (23 January)