The Prime Ministry Inspection Council will investigate the deaths of engineers Hüseyin Başbilen, Halim Ünsem Ünal and Evrim Yançeken, which occurred between 2006 and 2007.
The General Staff's Military Prosecutor's Office had earlier concluded an investigation into the deaths of the engineers, saying there were insufficient grounds for legal action.
Erdoğan ordered the investigation following a letter from the family of Başbilen, requesting that the engineers' deaths be reinvestigated.
Başbilen, a mechanical engineer who worked for ASELSAN for 10 years, was 31 when he was found dead on Aug. 7, 2006, in his car in Ankara's Pursaklar district. He was working on a critical project that would have largely freed the Turkish defense industry from depending on foreign technology.
Ünal was an electrical engineer. He was 29 when he was found dead near Lake Eymir in Ankara -- killed by a single bullet to the head -- on Jan. 17, 2007. He was working on a critical project in Mikes, an ASELSAN subsidiary, concerning the modernization of F-16 fighter jets.
Yançeken, also an ASELSAN electrical engineer, reportedly killed himself on Jan. 24, 2007 at age 26 by jumping off the sixth floor of his apartment building. All three cases were closed by the prosecutor's office as suicide cases with little or no investigation.
Başbilen's family never believed his death was suicide. His mother, Kezban Başbilen, had earlier applied to the prosecutor's office demanding the case be reopened. This only became possible in 2011 as part of the Ergenekon investigation. Vehbi Başbilen, the father, says the lack of blood splatter on the windshield and the fact the car windows weren't broken, coupled with deep cuts on the left wrists and the throat of his son, indicated that his death wasn't the result of a suicide. Başbilen had gotten married a month earlier and had no apparent reason to kill himself.
Ünal's family has also long said they did not believe their son's death was suicide because he was a young man who was full of life and energy. He also had plans to marry his girlfriend, a doctor. In fact, he died only three days before his wedding, according to his father, Şemsettin Ünal.
The deaths of the engineers are now being investigated again as part of the ongoing probe into a gang that faces accusations of making use of prostitutes, blackmail and espionage. There are 56 suspects in the investigation, including military officers.
All three were assigned to encryption and decryption projects at ASELSAN and had worked on highly strategic projects in the past.
The police are looking for clues that might link the suspicious suicides to the gang because the indictment indicates the gang made a decision to “destroy” individuals involved in military or strategic projects in which the gang had failed to influence their outcome. The gang used blackmail to get crucial national security documents from employees and bureaucrats in key projects to then sell the information to other countries. The prosecution accuses the gang of stalling and sabotaging many projects, but it also says the gang resolved to kill people working on projects in which it could not intervene.