Eyeless in Cooley — David M. Kiely

In 2000 an octogenarian retired schoolteacher is brutally murdered in the little town of Carlingford, close to the border that divides Ulster from the Irish Republic.
Is it a paramilitary killing? Or something infinitely more sinister?
Blade Macken, detective superintendent with Dublin's elite Special Branch, is assigned to the case.
But forces higher than the law are attempting to thwart his investigations. Using the age-old strategy of "divide and conquer," they succeed in isolating Macken from his partner, the lovely Detective Sergeant Orla Sweetman, who finds herself and her family under threat from enemies unknown.
Nothing is what it seems at first blush in this complex riddle. To solve it, Blade has to dig back into history -- and expose a very murky Vatican secret. . . .