A security guard posted at the official residence of Water Resources Minister Pawan Kumar Bansal allegedly shot himself dead in the wee hours on Sunday, police said.
Shamling of Meghalaya Armed Police shot himself in the head with his service gun at the 6-Ashoka Road residence of Bansal at around one am, they said.
The victim, who was in his late twenties, was posted at the minister's residence for the past few months.
Family problems may have led Shamling to take the extreme step, police said, adding no suicide note was recovered from him.
"Prima facie, it appears to be a suicide. But we are awaiting postmortem report to be sure that there is no foul play," he said.
Shamling's family is to reach the capital on Monday.