KABUL, Afghanistan — A wave of betrayal has left at least 17 Afghan policemen dead in the past 10 days — all killed in their sleep, at the hands of those close to them.

Early Thursday morning, an Afghan policeman unlocked the door of the check post where he was stationed in Oruzgan Province and let in his friends from the Taliban, who helped him attack his sleeping colleagues with knives and guns, eventually killing four and wounding eight.

On Sunday, a local police commander in a remote northern province, Jawzjan, shot to death, in their beds, five men under his command and fled to join the Taliban.

And on Dec. 18, a teenager, apparently being kept for sexual purposes by an Afghan border police commander in southern Kandahar Province, drugged the commander and the other 10 policemen at the post to put them to sleep, and then shot them all; eight died.