0251 GMT February 22, 2018
The state-run Anadolu news agency said on Tuesday that Oguz Guven, the editor of Cumhuriyet newspaper's online edition, was formally arrested Monday evening.
He had been taken to Istanbul police headquarters on Friday.
A court issued a warrant for the arrest of Guven after the newspaper posted a message on Twitter about the death of Mustafa Alper, the chief prosecutor of the southwestern province of Denizli, who was killed in a traffic accident last week.
The online breaking news, which was deleted in 55 seconds,described Alper as having been "mowed down" by a truck.
Citing the court decision, Anadolu said the tweet's wording was chosen to create a "perception of warning" for prosecutors working against a network run by Fethullah Gulen, a Turkish cleric based in the United States.
Reporting Guven's testimony, Cumhuriyet said the news was posted in a hurry, leading to an error in language.
Guven has also defended himself by saying that the phrase "mowed down" is often used to describe traffic accidents and was not ill-intentioned.
"We did not aim to commit a crime," the editor said.
On Tuesday, Turkish Prime Minister Binali Yildirim said the judiciary would "do what's necessary to people using inappropriate expressions" following Alper's death.
Alper filed the first indictment against Gulen’s network following the coup attempt. The Turkish government blames Gulen for orchestrating the coup, which he denies.
Twelve journalists and senior staff members of Cumhuriyet are imprisoned pending trial on charges of "aiding terrorist organizations."
The newspaper is known for its independent reporting. Last year, the daily’s former editor-in-chief, Can Dundar, fled to Germany after a Turkish court sentenced him to five years and 10 months in prison over a May 29, 2015 story that exposed trucks of Turkish National Intelligence Organization (MIT) carrying about 1,000 mortar shells, hundreds of grenade launchers and more than 80,000 rounds of ammunition for light and heavy weapons to Takfiri terrorist groups in neighboring Syria.
Figures show 165 journalists are behind bars in Turkey. Over 47,000 people have been arrested since the failed coup.
Turkish officials said late last year that some 82,000 people had been investigated in connection with the coup attempt. Tens of thousands of the people have been suspended, dismissed or jailed.