However the governor rejected pleas for clemency for the three others convicted of the assassination.

The assassination shocked India

The murder of Rajiv Gandhi in May 1991 by a suspected Tamil Tiger suicide bomber shocked India.

The authorities promised that his killers would be speedily brought to justice, but from the outset their investigation was slow -moving and complicated.

Lengthy investigation

Initially 41 people were accused of playing a role in the murder, including the leader of the Tamil Tigers, Velupillai Prabhakaran, and two other senior members of his organisation.

These three were never captured by the Indian authorities.

Twelve more suspects were either killed in the bomb blast itself - including the woman carrying the device - or died before the trial opened.

That meant that only 26 people were prosecuted for the murder and, of those, 19 were cleared and three others sentenced to life imprisonment.

Four of the defendants, however, were sentenced to death in January 1998.

Appeal

The decision on whether or not this sentence would actually be carried out became a legal and political hot potato.

President Narayanan has to seek the cabinet's advice

Nalini and her husband Muruggan, one of other three sentenced to death, had appealed for mercy on the grounds that their seven-year-old daughter would be orphaned if both of them were hanged.

Now that Nalini has been reprieved, the exhaustive appeals process of the other three condemned is by no means over.

They still have the right to make a last-ditch appeal for mercy to the Indian president, K R Narayanan.

But before the president makes his decision, he is constitutionally bound to seek the advice of the Indian cabinet.

That could put the prime minister, Atal Behari Vajpayee, in a difficult position.

Pressure

On the one hand he will be under pressure from some Tamil constituents of his coalition not to allow the sentence to be carried out.

Public executions are not common in India, and the prime minister will be under pressure from political liberals to urge the president to be lenient.

On the other hand, such was the sense of outrage in India over the circumstances of Rajiv Gandhi's murder - especially among Mr Gandhi's Congress party - that the cabinet and the president will be under similar pressure to show no mercy.