After the sniper attack, it is declared that there were 5 wounded and 4 dead. Later, Morland declares that the shots alternated between kills and wounds, to hide the sniper's skill, a fact which Sherlock appears to confirm (also confirming that Morland does indeed have information about this). However, for these facts to mesh, both the first and last shot would have to have been wounds, to make the numbers work. When Sherlock talks to Det. Bell, he confirms that Frank Bova, who was killed, was the first one shot.
When Holmes and Watson are going through the dead snipers belongings Watson comes upon an incorrectly filled-in sudoku puzzle, Holmes deduces that part of it is a Swiss bank routing number. He pronounces "routing" as rhyming with "out" (the American way) not as with "oot", as the British do.