The Bitterness of Olives by Andrew Brown

Second Hand 

"'Why can you not be friends anymore?' It was the story of his country, he supposed. Perhaps they could have been friends. Perhaps they were once. The reasons were complex, full of feeling, disappointment, resentment. And, of course, betrayal. This was the Middle East after all. Avi Dahan, a retired detective mourning his beloved wife in Tel Aviv, and Khalid Mansour, a Palestinian doctor confronting the precarious reality of living in Gaza City, are still reeling from the political fallout that jeopardised their delicate friendship. When a mysterious corpse scarred by history and forbidden love shows up in Khalid's emergency room, he reaches out to Avi for help. Though the detective is the only one who might be able to assist, he is the last person on earth to agree..."--Back cover.