The photo leaked on the internet and international media.
I am translating from http://www.tvxs.gr/v1407 (where you can also see the photo):
Exclusive: The photographer of the best picture of the days got fired
The photographer of [the newspaper] Eleutheros Typos Kostas Tsironis, who took the photos of the policemen aiming at demonstratoes gor fired from the newspaper. The photographs were taken on Sunday afternoon on Alexandras str. K. Tsitonis handed them in a litle later to the editor in chief of the newspaper Serafeim Kotrotsos. According to what the photographer said to Tvxs, Mr. Kotrotsos declared at the beginning that this is a major journalistic success. Then, howevr, he told him that he wanted to make sure that it was a shooting gun and not a flashbomb pistol. The photographer assured him that indeed this was a gun [specifies the make] 9mm., of the ones that don't have a safety catch. In order to confirm this, he showed him one more photo in which one could see the [part of the gun]. In communication Tvxs had with him, Mr Kotrotsos stated that he could not publish them before he was assured by specialists, since it had to do with an explosive political issue.
On Monday specialists were asked, who confirmed that this was a shooting gun. On the same day in the afternoon, K. Tsironis was informed by the graphic designers who were designing the paper that the photographs had been withdrawn from the first page of the issue they were preparing for Tuesday. He complained to his supervisor at the photoreportage department, who told him that the photos 'would perhaps be published in the inside pages'. The conversation took place in the presence of many journalists who confirmed it to Tvxs. In the same conversation, the photographer siad that the news that these photos existed had already leaked and that, if they were not published on the first page, the newspaper would miss a great journalistic success.
Eventually, the photographs were published on Tuesday on the inside pages of the paper, while they had already leaked to international news agencies and they were circulating on the internet. The photographer was notified not to cover the funeral of Alexis Grigoropoulos and a little later he was informed he was fired. S. Kotrotsos stated to Tvxs that he intended to publish the photos and that the photoreporter was fired because he violated his exclusive contract with "Eleutheros Typos" by leaking the photos. However the photographer maintains that it is an attempt of political censorship. He says that he is not personally responsible for the leak, since many employees in the newspaper had access to the photos after he handed them over. He added that, if they hadn't leaked, "they would never get published".
After the publication of the photos, the police announced that they are investigating the incident. Nobody [from the police?] has been in touch with the photographer.