Relatives of four people killed during an attack in India's Gujarat state last year have demanded that the inquiry into the killings be moved out of the state.
Fifty-eight Hindu activists were killed in the attack
Fifty-eight people were killed when a train carrying Hindu activists was allegedly torched by a Muslim mob in the town of Godhra.
The incident led to riots in Gujarat in which more than 1,000 people, mostly Muslims, were killed.
The families accused right-wing Hindu political parties of interfering in the conduct of the inquiry, by pressing relatives to give only limited statements.
The Hindu activists were travelling from the north town of Ayodhya, the location of a disputed religious site.
Some of the relatives have appealed for an end to organised Hindu trips to Ayodhya.
Some 56 people are being held in prison, charged in connection with the Godhra attack.
More than 70 people have so far been arrested for alleged involvement in the fire-bombing of the train.
In recent weeks, a controversy has broken out over another case involving the burning of 12 Muslims by a mob in the riots that followed the Godhra attack.
Twenty-one Hindus were acquitted of killing the Muslims in a controversial ruling last June after many of the prosecution witnesses withdrew their evidence.
Violence engulfed the state for weeks
Last month, India's Supreme Court came down heavily on the Gujarat Government's handling of the case, after a key witness said she lied in court after being threatened by senior right-wing political figures.
The Godhra incident sparked some of the worst religious riots seen in India since the country came into being in 1947.
Independent estimates put the number of people killed by the mobs at closer to 2,000.
Gujarat's hardline Hindu chief minister, Narendra Modi, described the violence as a "natural reaction" to the Godhra attack.
He was heavily criticised for failing to stop the violence, but no action was taken against him.
Mr Modi, a member of the BJP, the pro-Hindu party leading the central government coalition, went on to win state elections for the BJP last autumn.