Akyürek, who was the police chief in the northern Black Sea city of Trabzon when Dink was assassinated in 2007 by a Trabzon youth, was arrested on Friday after he was brought before a court in Istanbul. Akyürek, who later served as the head of the National Police's intelligence unit, faces charges of negligence for failure to act despite knowing that Dink would be murdered by a teenager motivated by a police informant.A new investigation into the murder plot has revealed police officers and prosecutors linked to the shady Gülen Movement engaged in a cover-up to help the murder suspects.A mustachioed Akyürek entered the sprawling court complex in Istanbul's Çağlayan district on Friday morning. The police chief, who loudly denied allegations against him in media outlets and TV channels linked to the Gülen Movement, was quiet as he was escorted into the courthouse by police officers. He only muttered to a throng of journalists that surrounded him "forgive any wrong I've done to you."He refused to testify at the police station to which he was initially brought on his lawyers' advice. After a four hour interrogation by the chief prosecutor, he was referred to the court and the prosecutor requested judges to order his arrest on charges of committing a premeditated murder through an act of negligence, forgery in official documents, gross misconduct for failing to warn authorities about the murder and for reportedly destroying electronic logs regarding the murder investigation.Following a removal of the ban on the investigation of public officials in relation to the case in June 2014, the investigation into the murder of Dink - who was shot outside the offices of Agos daily where he served as editor-in-chief - was renewed. This led to officials, including the former Istanbul police chief, deputy governor and other high-ranking officials in the city at the time of the murder, being summoned for questioning.The prosecutors also interrogated former police intelligence director Sabri Uzun and intelligence chiefs Akyürek and Ali Fuat Yılmazer.The Gülen Movement, which is run by U.S.-based cleric Fethullah Gülen, is accused of running a "state within a state" through its infiltrators in the police and judiciary. The movement is reportedly behind controversial trials that have seen the imprisonment of military officers, journalists and critics of the group.An investigation by previous prosecutors who worked on the murder case revealed that they dismissed allegations about Akyürek and Yılmazer. Muammer Akkaş was the last investigator of the murder who assumed the case in 2010. Akkaş, the chief prosecutor in the infamous Dec. 25 probe that sought to discredit the government by implicating those close to the government and the Justice and Development Party (AK Party) with charges of corruption, deliberately stalled the case according to media reports.Akkaş and other prosecutors did not investigate the allegations that Akyürek deleted electronic records and telephone logs within the National Police that would help shed light on the murder, according to reports in the Turkish media. The prosecutors also did not investigate similar allegations towards Yılmazer. Security camera footage at the time of the murder was not properly examined, and the role of police intelligence officials and gendarmerie officers both in Istanbul and in the northern province of Trabzon, where the suspects hailed from and where they allegedly planned the murder, were not investigated. The prosecutors reportedly did not look into the phone conversation logs of the suspects well enough to establish their connection with each other and other likely suspects, and officers at the Istanbul police department hid evidence regarding the suspects' connections. The prosecutors are also accused of not investigating contradictions in the testimonies of the murder suspects.Sabri Uzun, who was head of the National Police Intelligence Department, had claimed his subordinates hid tip-offs warning against the murder of Dink. Questioned about the murder, Uzun said Yılmazer hid an intelligence report from him regarding a plot to kill Dink.Yılmazer, who was the predecessor of Akyürek as the head of the intelligence unit, is currently in prison for a separate case involving illegal wiretapping, while Akyürek was removed from duty amid a major reshuffle in Turkish law enforcement last year. Earlier, he was suspended over allegations of destroying and leaking secret documents regarding the Dink investigation. Testifying to prosecutors recently, Akyürek admitted that he was aware of a planned murder regarding Dink after one of his subordinates presented him an intelligence report. He told prosecutors he did not remember the details, and thought that the Istanbul and Trabzon police directorate had "taken [the] necessary measures."Ogün Samast, who is currently in an Istanbul prison for Dink's murder, told prosecutors that the Trabzon police helped him and his accomplices, and said Yılmazer and Akyürek had knowledge of the plot in his new testimony last year.