Prominent Turkish politician Muhsin Yazıcıoğlu’s family is fighting to prove the role the Gülenist Terror Group (FETÖ) played in his death, which occurred in a shocking helicopter crash 15 years ago.

Yazıcıoğlu, the founder of the Great Union Party (BBP), was killed along with five other people accompanying him, when their helicopter crashed in the northern mountains of Kahramanmaraş province on March 25, 2009.

Three trials have been conducted over allegations of negligence during search and rescue efforts following the crash, while new reports are expected to be released in the main ongoing investigation.

The late politician's family had long voiced suspicions over the "accident" and had urged investigations into possible sabotage that caused the crash. Currently, a court is looking into allegations that members of FETÖ might have been involved in attempts to hinder investigations into the incident.

Yazıcıoğlu, his entourage and a journalist were traveling from one campaign stop to another ahead of the elections when their helicopter crashed.

Multiple investigations ended up with non-prosecution but Yazıcıoğlu's family pressed on with their legal battle over possible negligence that may have caused the crash and search efforts in its aftermath.

The most recent investigation is being carried out by prosecutors in Kahramanmaraş.

The family’s lawyer, Selami Ekici, told Anadolu Agency (AA) on Monday that the prosecution is preparing new reports upon their request regarding the weather movements and the carbon monoxide levels in blood samples of the crash victims.

Ekici has demanded the Kahramanmaraş prosecutors reverse an opinion in a 2011 report that stated: "The carbon monoxide levels in the victims’ blood could have increased since the samples were examined 15 months after the crash."

He also said the prosecution has welcomed his request that they investigate the possibility that the crash may have been caused by "three other jets" in the area.

"Shedding light on Yazıcıoğlu’s case means unraveling coup d’etats that could be mounted on this nation’s future," Ekici said and assured: "We will take this case to its resolution and hold perpetrators accountable."

The prosecution has been examining all evidence regarding the incident in light of the July 15, 2016 coup attempt FETÖ orchestrated in Türkiye, which killed 251 people and injured thousands of others.

In 2020, a court accepted an indictment against 17 defendants, including two former soldiers accused of ties to FETÖ. The indictment had accused the defendants of obstructing the earlier investigations and forging evidence, allegedly to conceal the terrorist group's possible links to the crash. It said the suspects misdirected the investigations immediately after the crash in line with direct instructions from FETÖ ringleader Gülen and other top members.

Yazıcıoğlu, a nationalist politician, was a staunch critic of FETÖ and Gülen was quoted as saying that Yazıcıoğlu was "removed with a divine blow" in a speech five days after the politician's death.

The indictment also accused the suspects, one of whom was a former colonel convicted for the attempted assassination of President Recep Tayyip Erdoğan during the 2016 coup attempt, of forging evidence and false secret witness testimonies through ambient wiretaps while abusing the pain of the victims’ families.

In January 2021, a trial based on the indictment was merged with another trial over the removal of a tracking device from the helicopter following the crash, which included 10 defendants.

In other trials on negligence in search and rescue efforts, a convicted FETÖ member and former police chief was sentenced to two years in prison for "gross misconduct" by writing a memo that said, "Yazıcıoğlu has a broken leg, an ambulance is currently taking him to the hospital."

Three other gendarmerie and police officers on trial were sentenced to 14 months for gross misconduct, while six other suspects were released.