His success was a dream come true for the tough port city of Sidon, Lebanon: a poor kid whose honeyed voice and ballads of love and heartbreak rocketed him to wealth and fame far from the gun-ridden neighborhood where he grew up.

Fadel Shaker became a superstar, hailed as "the king of romance," his songs wooing masses throughout the Arab world. He bought a vast, three-story villa with a swimming pool overlooking the city, cars, a private orchard and a beachfront restaurant.

Then last year, he renounced popular music as forbidden by Islam, grew a scruffy beard and took up with a hard-line sheik. Last month during a deadly turf battle with the Lebanese army in a Sidon suburb, he denounced his enemies and boasted that his group had killed two men. He has not been seen in public since and is believed to be in hiding.

The transformation of Shaker, 44, from a baby-faced crooner into an angry militant has left many dumbfounded. "We were all shocked," said Ahmed al-Naaj, a waiter in Shaker's former restaurant. "Why would a famous singer that the whole world knows change all of a sudden like that?" While even those close to Shaker cannot fully account for his turnabout, most people here see it as yet another symptom of worsening sectarian tensions in Lebanon. For years, many in this majority Sunni Muslim city have complained of the growing clout of Hezbollah, the Shiite militant group that is Lebanon's most powerful political force. But the civil war in neighboring Syria brought relations to a new low, with Hezbollah intervening to support President Bashar Assad and the Sunnis backing the rebels fighting for his overthrow.

New York Times