TAIPEI -- A trial for former leader of Taiwan Chen Shui-bian began on Tuesday, with the leader facing charges of illegally possessing classified documents.

Chen's office was raided by authorities on Sept. 25, 2008 following his loss in the island's leadership election to Chinese Kuomintang (KMT) Party Chairman Ma Ying-jeou.

Although most of the 1,300 sensitive documents uncovered during the raid should've been returned to Ma's office following his installation as Taiwan's leader, Chen failed to return the documents.

The prosecutors then ordered a second raid on Chen's office in 2010, uncovering another 688 classified documents. Investigators accused Chen in May 2012 of illegally possessing classified documents.

The court ruled that the trial will not be open to public due to its sensitivity.