VILNIUS — The explosion that damaged the Social Democrat party headquarters in Vilnius in October last year has been classed as unsolvable by prosecutors.

The mystery explosion on Oct. 12 left one man injured and sent shards of glass flying across the street as the bomb rocked the office. Initially the bomb squad ruled out the possibility of a gas leak, but no explosives were found either.

The Crime and Corruption Investigation Department of the Vilnius District Prosecutor’s Office Organized investigated the incident. Representative of the department Šarūnas Astrauskas told daily paper Vilniaus Diena that his team carried out all possible investigations, but rendered no results.

The case however cannot be closed either because the Social Democratic headquarters suffered material damage during the incident and one man who was in the office at the time suffered first degree burns to his face and hands.

The only information prosecutors had to work with was that the injured man had been using a cigarette lighter at the time of the explosion.