Police in the city of Mainz, Germnay, were accused of illegally using data from a COVID-19 tracking app to trace the contacts of a man who died leaving a restaurant, sparking an outcry.

Seeking witnesses of the incident, Mainz police (Polizeipräsidium Mainz) tapped into data from Luca, an app that helps track the COVID-19 pandemic in Germany by registering time spent in restaurants and pubs. 

The app also logs the patron's full name, address and telephone number - information that is protected under the country's data protection laws.

The police and local prosecutors in the case in Mainz successfully appealed to the municipal health authorities to gain access to information about 21 people who visited the restaurant at the same time as the man who died. 

Prosecutors apologised in the wake of complaints by local politicians, rights advocates and citizens. The local data protection authority also opened an inquiry. 

The incident raised concerns about data protection and public trust in COVID-19 tracking apps in Germany. It also provided ammunition for groups opposing pandemic restrictions and vaccination efforts.