Taiwan's high court on Friday opened its second trial on the island's ex-leader Chen Shui-bian's corruption cases by summoning Ma Yung-cheng and Lin Teh-hsiun, both former officials in Chen Shui-bian's office, and Chen Chen-hui, former treasurer of the ex-leader.

Chen Chen-hui pleaded guilty for her involvement in Chen Shui-bian's corruption cases during Friday's four-hour hearing, while Ma and Lin insisted they were not guilty, according to local media reports.

Chen Shui-bian himself was not summoned Friday.

Earlier on Friday, the high court upheld its decision to keep Chen Shui-bian in detention, for fear that the ex-leader would flee the island.

Chen was sentenced to life imprisonment by Taipei District Court on corruption charges on Sept. 11.

The court convicted Chen of embezzlement, money laundering, bribery and document falsification, with a fine of 200 million New Taiwan dollars (six million U.S. dollars).

Chen's wife Wu Shu-chen was also sentenced to life in jail by the court.