The first clue

Vansh stared at the mirror. Amritansh Pathak had left a few hours ago. He was unable to sleep. The bullet hole had complicated things. As he remembered the exact happenings of the night, Vansh recalled that he had not heard the distinctive sound of a sniper rifle. It would have been a very loud thuk or bang. Even if it were silenced, the van was very close to them. A light tsk should have been heard at least. He cursed himself for not noticing this before. He opened his laptop and inserted the memory stick Pathak had given him. It contained the CCTV footage of the area the night the PMs were in the Victoria Memorial. He saw the convoys pulling in and men getting out of the cars systematically. They checked around and then opened the doors for the VIPs. The men exited and joyously walked inside the monument, while the men kept milling around, expecting threats. He saw himself enter the frame now. He walked over to the man and talked to him. As Vansh saw himself turning around, he paused the video and zoomed in at the window of the van. He could see the end of the gun sticking out of it from the vantage point of the camera, but the men's faces were well hidden in the dark. He played the video in 0.1% of it's previous speed and waited. No bullet came out from the window, even as the van exited from the scene. Vansh now focused on the tree on which the bullet had hit and replayed the video. As the bullet came, he could see that it was coming from an elevated angle. He traced the bullet backwards and saw that it had come from a building opposite to the monument. He sat back and sighed contentedly. The night had become more productive than he had imagined. Pathak had gone back to his office to show his techies the other code that they had received after solving the crossword and he had got answer as to where the bullet had come from. The men in the van had been waiting for the PMs to come out. They had a custom sniper rifle. A custom sniper with an inbuilt stand and different design. Vansh immediately knew which gun it was. It was a QBU-88. A Chinese sniper.