A special inquiry commission probing the assassination of Indian Prime Minister Rajiv Gandhi resumed hearings Monday.
The Jain Commission is studying various allegations claiming government officials were involved in a high-level conspiracy to kill Gandhi.Gandhi was assassinated in 1991 while campaigning in India's southernmost state, Tamil Nadu.
More than 20 people accused of the crime await trial, which has gone through lengthy and controversial delays since it was first convened in mid-1993.
Many theories surround Gandhi's murder, including one that claims the involvement of separatist rebels from the Liberation Tigers of Tamil Eelam in Sri Lanka.
The guerrilla group denies any role in the killing.
As part of the Jain Commission's role, authorities have been studying whether government officials plotted Gandhi's death.
In a letter to commission chairman Justice Mihap Chand Jain, former Union Minister K.K. Tewary said the commission should look into possible links between former presidents Giani Zail Singh and R. Venkataraman and the Gandhi killing.
Both former presidents who served under Gandhi have dismissed the allegations as preposterous.
Venkataraman was openly critical of Gandhi's rule, claiming the son of former Prime Minister Indira Gandhi had little experience in politics.