Prosecutors stayed at Chen's home in downtown Taipei for about three and a half hours to question Wu Shu-chen, Chen's wife, and their daughter Chen Hsin-yu, according to local media.

A standby ambulance was sent to wait outside their living quarters in case wheelchair-bound Wu Shu-chen need any medical care during questioning, TV footage showed.

Spokesman for the prosecutors did not release the details of the questioning but said the former leader's wife did not black out during the process.

Their daughter was interrogated as a witness as she had not been listed as a suspect in the case, the spokesman said.

The questioning came three days after Chen Shui-bian was detained for alleged involvement in overseas money laundering and corruption on Wednesday.

On Friday Chen's son, Chen Chih-chung, and daughter-in-law Huang Jui-ching were also questioned as suspects in the corruption probe.