14.04.2026 14:14
The new evidence that emerged in the Gülistan Doku investigation moved the file to the axis of suspicion of murder and evidence tampering. The claim that the SIM card taken from the family was not submitted to the prosecutor's office added a different dimension to the investigation. The statements of secret witnesses and the secret note left to the family's lawyer gave a new direction to the missing person case that has been ongoing for years.
The investigation into the disappearance of Munzur University student Gülistan Doku in Tunceli has taken a completely different dimension with new information entered into the prosecutor's file, regarding allegations that have been discussed for years. An anonymous note left at the family lawyer's office in 2022, the striking statements of a secret witness codenamed "February" who emerged in 2025, and subsequent technical examinations shifted the case from an ordinary missing person's file to an axis of suspicion of murder, concealment of a corpse, and tampering with evidence.
ALLEGATION: "THE GOVERNOR TOOK THE SIM CARD BUT DID NOT HAND IT OVER TO THE PROSECUTOR'S OFFICE" One of the most striking developments was the examinations conducted on the SIM card belonging to Gülistan Doku. While the unrecovered phone and SIM card belonging to Gülistan Doku were reissued by her family, it was determined in considerable detail that they were requested and taken from the family by the governorship, but not handed over to the investigation authorities, and that Gülistan Doku's accounts were accessed and interfered with.
In her statement to the prosecutor, Gülistan Doku's sister, Aygül Doku, used the following statements: "The SIM card for the GSM line registered in my mother B. D.'s name, which was in my sister's use, was reissued by going to the dealer three days after my sister's disappearance. However, I was not at the dealer when the SIM card application was made. To my knowledge, my other sister B. D. and my brother R. D. were at the dealer when the SIM card was being issued. We used this SIM card by inserting it into my mobile phone and also into the mobile phone of my sister B. D.'s friend H. Y. A., hoping 'maybe someone will contact us, some news about Gülistan will come.' After we reissued the SIM card, the then Governor of Tunceli, Tuncay Sonel, in the presence of my uncle M. N. K., my brother R. D., my mother B. D., and my father H. D., said he had acquaintances in Ankara and could access any information and documents belonging to Gülistan from within the SIM card. We all heard him say this. However, we did not give him the SIM card at that moment. More precisely, I remember we did not give him the SIM card at that time. But from what I heard from my sister B. D., while B. D. and H. Y. A. were at a cafe, multiple police officers suddenly approached them and took the SIM card from her before my sister could even look at Gülistan's messages."
According to evidence entered into the case file; a witness, who was working at the Tunceli Provincial Directorate of Social Services at the time, is still working at the Tunceli Governorship, and was one of the persons assigned by the then Governor of Tunceli, Tuncay Sonel, to be with the family, stated in his testimony regarding this part: Aygül Doku told him that the Governor called them to his office and said, "Did you issue a SIM card? Give it to me quickly, I will hand the SIM card over to the prosecutor's office." The witness also relayed that when he asked Şükrü Eroğlu, the then governor Sonel's bodyguard, "Is there any development regarding the investigation?" Şükrü told him, "The Governor took the SIM card from the family and handed it over to the prosecutor's office."
However, the SIM card was not handed over to the prosecutor's office as claimed, and it was determined that it was placed under judicial custody about a month later with Aygül Doku's wet-signed, handwritten petition.
Sister Aygül Doku AYGÜL DOKU WAS SENTENCED TO 5 MONTHS IN PRISON On March 7, 2020, Engin Yücer, the stepfather of Zeinal Abakarov, one of the suspects in the disappearance of Gülistan Doku and a former police officer, wanted to move his house in Tunceli. A case was filed against sister Aygül Doku, who prevented Yücer from moving his house before the investigation was completed and a criminal examination was conducted in their home, upon the complaint of Engin Yücer on charges of "damage to property, threat, and insult." As a result of the case, Aygül Doku was sentenced to 5 months in prison and an administrative fine of 2,250 TL.
PUBLIC OFFICIALS WERE ASSIGNED AROUND THE FAMILY Contacts around the family were also re-examined in the investigation. The file also included witness statements that some public officials of the time were assigned to be constantly present around the family. The statements indicated that the then governor directed some names to be with the family, and it was reflected in HTS records that Umut Altaş, a close friend of Mustafa Türkay Sonel, called Gülistan Doku's sister Aygül Doku intermittently months after the incident.
THE TURNING POINT OF THE FILE: A NOTE, A WITNESS The most striking turning point in the Gülistan Doku investigation conducted by the Tunceli Chief Public Prosecutor's Office occurred with two consecutive developments years later. The first was the anonymous note left in front of the family lawyer's office in 2022, assessed to have been typed with a typewriter. That note recorded that Gülistan Doku had a relationship with Mustafa Türkay Sonel, the son of the then Governor of Tunceli, Tuncay Sonel. The second major turning point was the statements of the secret witness who testified in 2025 under the codename "February." These two developments fundamentally changed the direction of the investigation that started with a missing person report.
SUSPICIOUS VEHICLE MOVEMENTS ENTERED THE FILE Following the tip-off note, PTS records regarding the vehicle used by Mustafa Türkay Sonel were examined in the technical data entered into the prosecutor's file. According to the records, the vehicle's suspicious traffic and its route passing through remote, mountainous, and desolate areas away from social life zones at night hours drew attention.
Meanwhile, it was noted that in the vehicle, Türkay Sonel's close friend Umut Altaş was in the passenger seat, yet he was not recorded as being inside the vehicle during some passages.
It was recorded that the mobility detailed in the file could not be explained by ordinary night traffic. It was learned that Altaş's family members were detained, and a warrant and red notice process was initiated against Altaş, who has not returned to the country from the USA for a long time.
SECRET WITNESS "FEBRUARY" FUNDAMENTALLY SHOOK THE FILE The development that created a real earthquake effect in the investigation occurred in 2025. A person requesting confidentiality of identity contacted JASAT and explicitly stated that Gülistan Doku was killed; then shared shocking details that even shocked the investigation authorities.
The secret witness provided quite detailed narratives about Gülistan Doku being taken from near the bridge on the day of the incident and about what happened afterwards. The secret witness changed location multiple times due to concerns about the corpse being found. Following the statement, a suspicious void resembling a grave was detected with underground scanning devices at a point described.
According to prosecution sources, these findings have strengthened the claim that the body was moved. The overlap between the technical findings and the statements of the secret witness was interpreted as a sign that the case has entered a new phase. Search and excavation operations were also carried out with underground imaging devices in other identified locations.
THE CASE IS NO LONGER JUST A "MISSING PERSONS" CASE At this stage, the Gülistan Doku investigation has moved beyond the framework of a "missing young girl" as it was initially reported to the press in the early years. The new investigations, which began with the mysterious note left at the lawyer's door in 2022, combined with the secret witness's accounts in 2025 and the subsequent excavation, technical data, and witness statements, have placed the case at the center of much more serious allegations.
It is stated that the Chief Public Prosecutor's Office is conducting the investigation in a multifaceted manner, including the possible role of public officials, abuse of influence, potential evidence tampering, and suspicion of premeditated murder. It is noted that as the Gülistan Doku investigation, which has troubled Turkey's conscience for years, progresses, many more details may be reflected in the press.