Police in Munich are investigating a mystery: More than 1,000 stickers were put on gravestones and wooden crosses at three cemeteries in the German city, without any indication of where they came from or why.

Cemeteries in Munich allow QR codes as memorials on headstones, Mr. Hoerauf said, and for more than a decade, people whose loved ones are buried in cemeteries around the world have uploaded photographs and other digital keepsakes to create online memorials that can be viewed via QR code.

German police are investigating after over 1,000 QR-code stickers were slapped onto graves across three cemeteries in Munich. The small stickers, when scanned with a mobile phone, show the deceased person’s name and their location in the cemeteries.

The stickers have appeared at the Waldfriedhof, Sendlinger Friedhof and Friedhof Solln cemeteries in the southern German city. Police are investigating the incident.

Initially, some thought the QR code mystery may have something to do with Nazi propaganda, partly due to a past incident in 2004

The local police have requested those who have witnessed anybody putting the stickers on the graves in Munich to reach out to the respective cemetery's administration.

More than 1,000 stickers have appeared on gravestones at three cemeteries in Munich, Germany, without any indication of where they came from or why, sparking a police investigation