The two men were shot by two men wearing Afghan police uniforms.
The inquest heard an intelligence report that said "insider threat" was difficult to detect. Insurgents and the Taliban used this kind of attack as a tactic and there had been no increase in this kind of threat.
More top news
A drier, brighter but colder day than Thursday. Sunny spells are likely, although it will turn cloudier in the afternoon.
A generally fine and dry day. Sunny in the morning, with thickening cloud and strengthening winds in the afternoon.
A cold night, with clear spells developing for most. Tomorrow, generally fine and dry with plenty of sunshine, especially in the morning.