The Istinomer fact-checking portal said on Monday that the photograph of Serbian President Aleksandar Vucic signing the book of condolences at the Belgrade elementary school where a student killed 9 people showed indications of digital manipulation.

Istinomer said that it checked the pictures published by pro-regime media with help from digital experts at the Belgian Knack fact-checking portal.

Vucic denied claims that he never went to the school where the mass shooting happened. He told the pro-regime Happy TV that he did go to the school, claiming that he wrote a message on almost an entire page of the book of condolences. “Are you trying to say that one of the Cobra (military police detachment that guards the president) photoshoped something,” he said.

“Social media users said they suspect the picture was photoshoped because of some visual discrepancies. Without getting into whether the president was at the school or not, Istinomer worked with experts at the Belgian fact-checking portal Knack on a detail and deep photo-forensic analysis and determined that the photograph contained traces of digital manipulation which indicate that it is not completely authentic,” the portal said.

The picture was originally published by the pro-regime Kurir and Republika portals and Tanjug news agency. It was also shown in parliament by ruling coalition MPs claiming it was indisputable proof that Vucic visited the school. The picture was published after opposition officials criticized the president for not going near the school after the mass shooting.