Gu and a family aide, Zhang Xiaojun, are accused of poisoning Neil Heywood, a British businessman who was found dead in the southwestern Chinese metropolis, Chongqing in November.
The trial is the latest phase in the fall from grace of the prominent family of Bo Xilai, Gu's husband, who until earlier this year had appeared destined to join the elite committee of leaders at the top of China's ruling party.
The saga has become the most sensational Chinese political scandal in recent years, creating an extraordinary set of challenges for the central government as it prepares for a once-in-a-decade leadership transition later this year.
Experts say if Gu and Zhang lose the trial, we cannot exclude the possibility of Bo Xilai's capital punishment. Recently, the Chinese police became suspicious about Bo Xilai's trying rebellion in Chongqing, and also tapping the Fu Jintao, the leader of Chinese's call. There are also high possibilities when Gu lose the trial, Bo Xilai's political followers would be completely exterminated.