I am translating from the blog http://skakistiko.blogspot.com/2008/12/18111985.html:
'This is the first page of the newspaper 'Ta Nea' of 18/11/1985 which went round the world. Michalis Kaltetzas (1970 - 17 November 1985) was a pupil who was killed during demonstrations on the anniversary of the Polytechnic uprising in 1985. [note: the uprising was on 17th Nov. 1973]. The policeman Athanasios Melistas, award winner for his "aiming abilities", shot Michalis Kaltetzas on the back of his head as the young man was running together with other demonstrators in Exarhia square.
At the link you can see the front page of 'Ta Nea' from 1985 and the youTube video from the shooting of Alexandros Grigoropoulos.
The policeman Athanasion Melistas was never punished.