Dhaka, Nov. 21 -- Gunmen are arriving at specific locations and targeting specific individuals with precision, in attacks that investigators say clearly bear the marks of planning. The shooters are paying no heed to their surroundings, firing multiple rounds to ensure death.

A string of brazen killings in the capital, carried out in full public view, has fuelled alarm and a swirl of questions. Speculation is rife over what lies behind these murders and who is involved.

Within days of two such killings in the space of a week, police have announced arrests, saying they have traced not only the gunmen but others involved. Yet a persistent question hangs over law enforcement: if police can track down suspects within days, why are they unabl...