4.  The applicant is a Turkish national, who was born in 1961 and he lives in Adana. 5.  On 16 November 1994 F.A. and her son, İ.A., filed a complaint with the gendarmes and submitted that they had received a threatening letter from the PKK. The letter which was written on purple paper and sealed with the symbol of the PKK read: “You have to change your statement concerning our friend or both of you will die.” F.A. and İ.A. stated that they had been summoned to give evidence in connection with an ongoing investigation against certain PKK members. They further maintained that they knew the person who had sent the letter. 6.  Accordingly, the gendarme officers initiated an investigation, which led to the arrest of the applicant. 7.  On 17 November 1994 the applicant was arrested on suspicion of sending threatening letters on behalf of the PKK. Samples of the applicant's handwriting were taken and sent to the laboratory for examination. 8.  The Regional Criminal Police Laboratory compared the handwriting of the applicant to the handwriting on the letter. It concluded that the characteristics of the applicant's handwriting had similarities with the handwriting on the letter. 9.  On 18 November 1994 the applicant gave a statement to the gendarmes and denied all the accusations against him. He submitted that he had no connections with the PKK and that he had not written the letter. 10.  The same day, he was questioned by the Adana public prosecutor. In his statement to the public prosecutor, he mainly repeated his police statement and denied the charges against him. 11.  The applicant was then taken before the Adana Magistrate's Court in Criminal Matters on the same day. He pleaded not guilty before the judge. He denied the allegation that he had carried out activities on behalf of the PKK. He further asserted that his signature which had been used for handwriting analysis had not been taken in accordance with the domestic legislation. After examining the expert report and the applicant's submissions, the court concluded that the sample of the applicant's handwriting which had been used for comparison had not been taken in accordance with the law. It accordingly concluded that there was not sufficient evidence to establish that the applicant had committed the alleged offence and ordered his release. 12.  In an indictment dated 26 December 1994, the public prosecutor attached to the Konya State Security Court initiated criminal proceedings against the applicant. He charged him with being a member of an armed gang under Article 168 § 2 of the Criminal Code. He based himself on the report of the Regional Criminal Police Laboratory which had concluded that the applicant's handwriting had similarities with the handwriting on the threatening letter sent to F.A. and İ.A. 13.  Before the court, the applicant contested the charges against him. He stated that he had no connection with the PKK and that the allegations were baseless. 14.  On 8 June 1995 the court ordered the Forensic Medicine Institute to carry out a handwriting examination. 15.  On 17 July 1995 the Forensic Medicine Institute sent a letter to the court and requested further specimens to make an accurate comparison. In this respect, they required the applicant to write down the text of the letter in small letters, and the text on the envelope in capital letters. The Institute further requested the applicant to submit specimens of his handwriting, which he had written in the past. 16.  After an examination of the above-mentioned samples, the Institute delivered two reports, dated 22 January 1996 and 22 January 1997. It was established that the characteristics of the applicant's handwriting had similarities with the handwriting on the letter and that the letter was written by the applicant. 17.  The Konya State Security Court held twenty-six hearings, the last on the 28th April 1997. 18.  On 16 May 1997 the case was transferred to the Adana State Security Court. Between this date and 14 October 1997 the court held seven hearings. 19.  In his final observations on the merits, the public prosecutor changed the accusation against the applicant and accused him of aiding an armed gang under Article 169 of the Criminal Code. 20.  In his final defence submissions, the applicant denied the allegations under Article 169 of the Criminal Code and stated that he had not written the letter and that he had no connection with the PKK. He further challenged the findings of the experts' reports. 21.  On 14 October 1997 the Adana State Security Court, which was composed of three judges including a military judge, found the applicant guilty as charged and sentenced him to three years and nine months' imprisonment pursuant to Article 169 of the Criminal Code. The applicant was further debarred from public service for three years. In its judgment, the court found it established that the applicant had sent a threatening letter on behalf of the PKK to F.A. and İ.A. who were to give statements against certain PKK members in connection with another criminal case. The court based itself on expert reports which had concluded that the letter was written by the applicant. 22.  After holding a hearing, on 30 June 1999 the Court of Cassation dismissed the applicant's appeal.