The case of Gülistan Doku, who went missing in Tunceli, eastern Türkiye, in January 2020, has remained unresolved for more than six years despite extensive search and investigation efforts.
Doku, a 21-year-old university student, was last seen on Jan. 5, 2020, near the Sarısaltuk Viaduct in Tunceli. Search teams conducted extensive operations to locate her, but her whereabouts remained unknown.
A new development emerged after Umut Altaş, a suspect wanted in connection with the investigation and detained in the U.S., was questioned by the FBI under Türkiye’s judicial assistance request.
Altaş was questioned by FBI and U.S. Homeland Security Investigations officials on Aug. 19 and 20 at the Moshannon Valley Processing Center in Pennsylvania. Turkish authorities had prepared 109 questions for the interview.
The FBI subsequently prepared a 34-page report dated Aug. 26 and sent it to Turkish authorities through the Turkish Justice Ministry’s Directorate General for Foreign Relations and European Union Affairs.
According to the report, Altaş alleged that Mustafa Türkay Sonel shot Doku inside a BMW on Jan. 5, 2020, while Altaş was sitting in the front passenger seat.
Altaş claimed Doku was sitting in the back seat when she objected to being followed. He alleged that an argument broke out before Sonel took a black handgun from the vehicle’s glove compartment and shot Doku.
Altaş said he looked at Doku and believed she was dead. He further alleged that Sonel ordered him to remain silent and help move Doku’s body to the trunk. Altaş initially refused but later said he helped place the body inside the vehicle.
He also alleged that Sonel called Şükrü Eroğlu after the body was placed in the trunk and spoke with him for 15 to 20 minutes. According to Altaş, Sonel later said his father would handle the situation.
Altaş claimed Sonel contacted him the following morning and told him not to speak about the incident. When Altaş asked where Doku’s body had been taken, he said Sonel indicated the Pertek area, a district in Tunceli.
Turkish Historical Traffic Search and license plate recognition records were also presented to Altaş during the FBI interview. The records showed Altaş near the Sarısaltuk Viaduct around 10:09 p.m. on Jan. 5, while Sonel’s phone was recorded in the same area. License plate records showed Sonel’s BMW traveling toward Elazığ at 10:17 p.m. and returning toward Tunceli at 10:30 p.m., with Sonel driving and Altaş in the front passenger seat.
Altaş said they returned to the bridge area to check whether cameras had recorded the incident. He alleged that Sonel told him a university camera would not record them but said he did not know who had deleted or disabled any footage.
Altaş also alleged that Sonel threatened to kill him and his family and offered him money to remain silent. He said he refused but claimed Sonel nevertheless placed money in his wallet.
The FBI questioned Altaş about other allegations, including claims that Doku had been pregnant and forced to undergo an abortion. Altaş said he had no direct knowledge but acknowledged making earlier statements based on what Sonel allegedly told him.
He also confirmed receiving a one-view WhatsApp video from Sonel showing someone holding body parts, although he could not confirm that they belonged to Doku.
When FBI agents directly asked whether Altaş had been with Sonel and Doku when Doku was killed and whether he had personally witnessed the shooting, the report said Altaş answered affirmatively.
The report also included a WhatsApp message Altaş sent to his father, Celal Altaş, saying, "Stop pretending. You were the one who silenced me.” Altaş acknowledged sending the message but said he did not remember why.
Authorities continue to investigate the disappearance of Doku, with the case seeing a series of new arrests and developments in recent months. At the beginning of September, another suspect was arrested after being referred to court as part of the latest wave of operations, bringing the number of people in custody in the investigation to 30.