A court in Istanbul on Tuesday sentenced journalist Pelin Unker to 13 months and 15 days in prison, along with an additional fine.
The sentence, along with a fine of 8,600 Turkish lira (€1,370, $1,570) was imposed for "insulting and slandering a public official."
Unker's report appeared in Turkey's secular, left-leaning Cumhuriyet newspaper, for which she no longer works. The allegations were linked to the "Panama Papers" series of revelations about offshore entities used by politicians, celebrities and companies.
Former Prime Minister Binali Yildirim and his two sons sued Unker in November 2017 over a report about the sons' alleged ties to five offshore companies in Malta.
Unker was not immediately jailed, and is still able to appeal. The journalist told DW that she would do so, but that she still expected a prison sentence.
"We had expected this sort of judgment," said Unker. "It was already expected on the last day of the trial that there would be a sentence. Indeed, there was always the feeling that a defense was pointless. The judgment was predictable. Here, journalism itself was punished."
"This has become part of life as a journalist," said the reporter, who filed for DW from Istanbul. "It's already at the stage where we meet our friends and acquaintances in courtrooms."
'More than questionable'
DW spokesman Christoph Jumpelt said that the developments concerning press freedom and freedom of speech in Turkey had been "more than questionable for a long time."
"With every unjust verdict against journalists, the Turkish government further restricts freedom of the press," Jumpelt said.
Yildirim served as prime minister of Turkey until July, when the position was abolished to make way for the executive presidency of President Recep Tayyip Erdogan, himself prime minister from 2003 to 2014.
Yildirim is currently the parliamentary speaker, and is set to run as candidate for mayor of Istanbul for the ruling Justice and Development Party (AKP).