LAWYERS and senior Congressmen admit Mahant Sewa Dass Singh, president of the Shaheed Pheru Man Shermani Akali Dal, is a key witness who could throw light on the conspiracy behind Rajiv Gandhi's assassination, involving Khalistani and Kashmiri militants and the LTTE. Sewa Dass has already deposed before the Jain Commission and since he was on the hitlist of various Punjab and Kashmir militant groups, he had been provided with Z-plus security. But in a curious move, the Punjab government, which was asked to provide cover by the home ministry, has scaled down his security and taken away his bullet-proof car. Sewa Dass fears the worst and believes that he could become the target of those who do not want him to testify in a court of law.