Back in February this report from Turkey got me interested:
The suspicious deaths of four engineers who were declared to have committed suicide might have been murder, according to a new indictment into an espionage gang within the naval forces.

All four men worked for ASELSAN, a defense industry giant that produces technology for the Turkish military. The deaths are 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.

Recently, the İstanbul Police Department's Anti-Organized Crime Unit requested the closed case files of Hüseyin Başbilen, Halim Ünsem Ünal and Evrim Yançeken -- who were reported to have killed themselves between 2006 and 2007 -- in order to re-launch an investigation. All three were assigned to encryption and decryption projects at ASELSAN and had worked on highly strategic projects in the past.
Was the police really interested in those suicides or was this one of those political investigations, not unheard of in Turkey, that are held simply to remove the suspects from their job?

Back in 2007 three suicides within six month were so suspicious that they led to an inquiry in the Turkish parliament. Nothing came out of it. Those engineers were allegedly working "a critical project that would have largely freed the Turkish defense industry from depending on foreign technology", "the modernization of F-16 fighter jets" and on software for a new tank. Their families did not believe they committed suicide but suspected they were suicided. Who then would have interest to kill them and why?

While the fourth suicide and the investigation looked suspicious I did not find enough to understand the real story. There were lots of rumors about those suicides but few verifiable facts and no obvious motive for murder. This recent news item though may now explain the reason for their death:
Turkey's Military Electronics Industry (ASELSAN) has produced a new identification friend or foe (IFF) system for Turkish jet fighters, warships and submarines and the new software, contrary to the older, US-made version, does not automatically identify Israeli planes and ships as friends, a news report said on Tuesday.

The new IFF has already been installed in Turkish F-16s and is expected to be installed in all Navy ships and submarines, the report, published in Turkish daily Star, said. It will be fully operational when it is installed in all military planes, warships and submarines.

The F-16 jet fighters, purchased from the US, came with pre-installed IFF software that automatically identifies Israeli fighters and warships as friends, disabling Turkish F-16s from targeting Israeli planes or ships. ASELSAN-made IFF will allow Turkish military commanders to identify friends and foes on the basis of national considerations.

Turkey was unable to make modifications to the friend or foe identification codes in US-made F-16s, while Israel was given a different version of the software allowing Israeli authorities to make modifications. Israel was also authorized to view the version given to Turkey, according to Star.
The killing of foreign engineers and scientists working on military or nuclear projects is a favorite pastime for the Israeli Mossad (see Iran, nuclear). But back in 2006 and 2007 when the first three engineers died Turkey - at least publicly - still had quite friendly relations with Israel. Then again, Israel does not really mind spying on its allies.

Turkey's president Erdogan is arguing quite loud against Israeli misdeeds. That gets explained with the killing by Israel of nine Turks on the Gaza flotilla ship. But there may be more behind Erdogan's turn from Israeli ally to foe. The sabotaging of an important Turkish military project through the killing of these engineers might well be another reason for the change in Turkish foreign policy.