Supreme Court today directed the Centre to inform it about the investigation on the aspect of conspiracy behind making of the bomb that had killed former Prime Minister Rajiv Gandhi in 1991.<br/><br/>The apex court asked the government about the probe being carried out on this aspect, after one of the convicts in the assassination case claimed that this issue has not been properly probed.<br/><br/>A bench headed by Justice Ranjan Gogoi sought result of re-investigation or further probe in the matter. The apex court fixed the matter for further hearing next week.<br/><br/>Rajiv Gandhi was assassinated on the night of May 21, 1991 at Sriperumbudur in Tamil Nadu by a suicide bomber at an election rally. 14 others were also killed then.