The Russian connection to a Berlin hit job that Germany doesn't want to talk about

Forensic teams examine the site where Chechen exile Zelimkhan Khangoshvili was killed.

Berlin, Germany (CNN)Murders happen in Berlin. They're not common -- the crime rate in Germany is currently at its lowest level in more than 25 years -- but as with all major cities, the occasional violent killing is all but inevitable.

What's far less common is for them to occur at noon, in the city center. And what's truly unprecedented is when the target is a former Chechen fighter, and the suspect an alleged Russian government hitman.
But that's exactly what happened on August 23.
    Zelimkhan Khangoshvili, a 40-year-old Georgian citizen of Chechen descent, was on his way to midday prayers at a mosque in the Moabit district of downtown Berlin.
    A man following him on an electric bicycle approached and shot him at close range twice in the head and once in the shoulder. Khangoshvili died instantly; his suspected killer was apprehended and remains in police custody.
    If the alleged assassin was trying to be discreet, it's fair to say he failed. Two teenagers saw him throwing a handgun, wig and bike into the River Spree, setting off a murder mystery that has gripped the country and raised uncomfortable questions about Germany's complex relationship with Russia.
    The suspect, who was carrying a Russian passport, was arrested within hours. But more than two months later, the case is still in limbo: the suspect won't talk, the Kremlin denies involvement, and Germany refuses to point the finger at Moscow without definitive evidence.
    The murder has also cast a dark shadow over the tens of thousands of other Chechen migrants living in Europe. Vulnerable to deportation, and rising anti-migrant sentiment, they say they're closely watching Germany's response to the incident.

    'We were in shock'