The thief took a mobile from the Dresden church in March this year and by April had managed to make enough international calls and download enough data to rack up a six-figure phone bill.
Baffled, church officials checked their records and found that the smartphone in question had indeed been missing for the past month, without anyone having noticed.
Police scoured the €310,280.28 bill and found several numbers that the thief had called regularly over the month. One of these was from the nearby Saxony town of Pirna, which was where they uncovered the likely identity of the culprit.
Church staff recognised a picture of the 21-year-old man, who they said had come into the parish hall in March to ask for money for a train ticket to Frankfurt. Neither they, nor the police know where the man is and authorities think he may have left the country.
It is not yet clear whether the man will have to pay the bill himself.