The family of Costas Tsalikidis, the Vodafone software engineer who allegedly committed suicide two days after spy software was discovered in the company's central system, yesterday filed a lawsuit against «those responsible» for complicity in his suicide or murder. In their lawsuit, the family claim that the engineer told his girlfriend that the company might close down and that it was «a matter of life and death» that he leave Vodafone. The family alleges that someone may have strangled Tsalikidis and then made it look like he committed suicide. They also claim that Tsalikidis was involved in a meeting with top Vodafone executives, including CEO Giorgos Koronias, on March 8 - a day before his death. The Communications Privacy Protection Authority (ADAE) heard from Koronias yesterday. Sources said he told the watchdog that someone working for Vodafone or Ericsson must have helped activate the spy software. He also said the program was deactivated immediately on being discovered because of fears for national security. Tsalikidis's brother, Panayiotis, met prosecutor Yiannis Diotis yesterday and gave him a notebook kept by Costas between 27 January and 28 February last year. The notes were in English and Greek and included a heading titled «If something goes wrong.» He also wrote that «something is not right at the company.» The notebook also had a lot of technical data, sources said. Police clashed with protesters in Thessaloniki during a march against the phone tapping yesterday. A police officer was injured in the clashes. Hundreds also marched on the US Embassy in Athens, accusing the USA of being behind the taps. A poll conducted by VPRC on behalf of Skai Radio suggested that 40 percent of people think that the tapping was done by foreign and Greek secret agents. Of those, 73 percent thought the USA was involved and 8 percent suspected Britain. Eight in 10 respondents said the taps are still going on and 55 percent said that Greece's national security is not being protected at all.