By Chris Hogg
BBC Taiwan correspondent
Three men in Taiwan have been charged in connection with the shooting of President Chen Shui-bian, according to investigators.
Chen Shui-bian was shot on the eve of the election
The men were arrested following the discovery of homemade bullets similar to those used in the attack last March.
A spokesman for the task force investigating the shooting said the men had been charged with weapons offences.
But police could not yet prove they were involved in the attack itself, the spokesman said.
Investigators believe that Taiwan's president and vice-president were shot on the eve of the presidential election with homemade bullets fired from a replica pistol, which had been altered to fire live ammunition.
At a press conference on Friday, police said they had arrested a man two months ago who was found to be in possession of such a weapon.
Police then detained two of this man's friends, whom they believe supplied him with the pistol and the ammunition.
Tests have shown the structure of the bullet casings found with these three men matched those used in the attack on President Chen.
They have now been charged with weapons offences, because otherwise they would have had to be released after spending eight weeks in detention.
However, there is no additional proof yet to link them to the shooting, a senior police officer said.
The task force set up to investigate the incident is under pressure to provide results.
Until now it has been unable to produce any firm leads, and next week Taiwan's parliament will attempt to force the president to set up a new independent investigation into the attack.
The opposition claims the shooting swung the vote in Mr Chen's favour, and has suggested it was staged to win him sympathy votes.