Four suspects were remanded in custody on Monday in connection with the 2007 murder of Turkish-Armenian journalist Hrant Dink.

As part of an ongoing investigation by Istanbul chief public prosecutor's office, seven suspects in total were detained and sent to Istanbul Court of Peace No: 2.

The court ruled that four of the accused would be detained for being members of the Gülenist terror-cult led by U.S.-based preacher Fetullah Gülen.

The four have been named as: former gendarmerie commander of Trabzon province Colonel Ali Öz; gendarmerie intelligence officer Sergeant Veysel Şahin; Sergeant Ecevit Emir from Istanbul provincial gendarmerie command; and gendarmerie officer Adem Sarıgöl.

The rest were released pending trial. Monday's fresh detentions, the number of remanded suspects has now reached 14.

Dink was murdered in broad daylight in front of his office in Istanbul on Jan. 19, 2007. He was one of the founders of the bilingual Turkish-Armenian weekly, Agos, and was considered one of the most prominent Armenian voices in Turkey.

Ogün Samast, who was aged 17 at the time of the killing, claimed he murdered Dink for "insulting Turkishness" and was jailed in 2011 for 23 years.

Since then, several prosecutors have become involved in the investigation, believing Samast was not the only person involved in the killing.

On April 20, 2007, Istanbul Public Prosecutors Selim Berna Altay and Fikret Seçen prepared an indictment of over 18 suspects, including Samast.

Istanbul High Criminal Court had accepted the indictment. However, the indictment was criticized since it only focused on Samast and would not reach other suspected perpetrators responsible for Dink's murder.

In July 2014, Turkey's Constitutional Court ruled the murder case had been an "ineffective investigation".

In Dec. 2015, another indictment called for the prosecution of 26 people on charges of "establishing an armed organization" and "neglecting their duties".

That indictment called for life sentences to be handed down to Ramazan Akyürek, a former head of Turkey's police intelligence, as well as Coşkun Çakar and Ali Fuat Yılmazer, both senior police intelligence officers.

The tenth hearing was held last week for the above three who have been accused of intentionally causing Dink's death and forming an "armed organization".

Recently, the murder case has been expanded to the gendarmerie in light of new evidence.

On July 3, 2016, two gendarmes, Abdullah Dinç and Yusuf Bozca, were arrested and remanded.

During his appearance at Çağlayan courthouse in Istanbul, Bozca said: "The Dink assassination was organized by members of FETÖ / parallel state structure and his murder then formed the basis of the [July 15] coup attempt."

On Aug. 6, a gendarmerie officer at Trabzon province's Intelligence Department Ergün Yorulmaz was remanded while three days later another gendarmerie sergeant Emre Cingöz was also jailed in Istanbul.

On Aug. 10, five other gendarmes were charged with being members of a terrorist organization and "complicity in premeditated murder" and detained.

Two days later, Ali Barış Sevindik, who was serving as a lieutenant at the time of the murder in Istanbul gendarmerie command's intelligence department, was put behind bars.