When Nasser Qaout went to investigate strange sounds in his sheep pen late at night, a gang of armed thieves shot him in the leg and made off with half his flock.

He and Palestinian police know who the thieves are - and even where they are - but a year and half later, they’re still in their homes about five kilometers (three miles) down the road.

Police say they can’t arrest the crooks because they live in an Israeli-controlled area, which Palestinian forces can’t enter freely. It’s a unique dilemma for Palestinian law enforcement: How to maintain security when criminals have more freedom of movement than police do.

The international community considers the Palestinians’ ability to handle internal security a prerequisite for independence. European countries gave $5.3 million last year to bolster Palestinian security forces, and the United States has given more than $160 million for that purpose since 2007.

The European and U.S. emphasis is on bolstering the strength of Palestinian President Mahmoud Abbas against the militant Islamic movement Hamas and similar groups. Israel is constantly demanding Abbas’ Palestinian Authority crack down on militants.

But Palestinian police also must fight common crime, and they say the jigsaw puzzle of security zones that cover the West Bank, dividing it between Israeli- and Palestinian-controlled areas, hampers their work. Israel occupied the territory in the 1967 Mideast war and maintains overall control, although international agreements have given the Palestinian Authority limited autonomy in some areas.

Palestinian police can only enter Israeli-controlled areas of the West Bank with permission, which they say is often difficult or impossible to obtain, making these virtual black holes ideal hideouts for criminals.

This can have dangerous - and sometimes deadly - consequences.

Officers can’t wear uniforms, carry guns or chase criminals on main roads that enter Israeli-controlled zones, making it easy for car thieves and drug dealers to escape, police said. Outlaws are also known to seek refuge in villages close to Israeli military installations or Jewish settlements, knowing Palestinians police won’t be allowed in to arrest them.

“Lawbreakers know they can flee to places where there are settlers and we will not be allowed to go after them,” said police spokesman Adnan Damiri.

Last year, a gunbattle that grew out of a family feud next to an Israeli army base near Hebron lasted three days because police couldn’t enter the area, said Hebron Police Chief Ramadan Awad. Seven people were killed in the fighting.

In the last two years, Palestinian police have deployed in towns like Jenin, Nablus and Hebron, reducing crime in areas they patrol, Palestinian and Western officials said.

But this has pushed crime into areas where police are forbidden to enter, the officials said. Borders between the two are often unmarked, meaning that civilians - and criminals - can pass freely, while police cannot.

No place better illustrates this than Hebron, where a heavily guarded, Israeli-controlled island, home to some 400 Jewish settlers, sits at the center of the West Bank’s largest city, with a population of about 170,000.

Israeli army checkpoints block entry to the Jewish settlements, but 40,000 Palestinians live in the surrounding Israeli-controlled zone and can move freely in and out of it. Most of the border around the Israeli zone is unmarked, but police know where it is and don’t cross it.

Awad said he gets calls daily about rampant petty crime that he can do nothing about in the Palestinian part of the Israeli-controlled area.

More dangerous, however, are two armed gangs that operate inside the Israeli zone, he said.

The larger one rustles livestock, deals drugs and steals cars, charging ransoms as high as $3,500 to return them, said Hassan Jabarin, Hebron’s chief investigator. The police have reports of 22 such thefts last year, but Jabarin suspects many more were not reported.

The gang’s leader is wanted on four counts of armed robbery and four of attempted murder, one against a police officer, Jabarin said. He has also personally threatened the lives of Jabarin and Awad by phone, Jabarin said.

He said police have been requesting permission for more than a year to enter the area where the gangs operate, which abuts a large Jewish settlement - to no avail.

Police say the difficulty they have obtaining permission shows a lack of interest by Israel in catching criminals who prey on Palestinians.

“Those who shoot at the settlers, they pick them up in half a minute,” Jabarin said. “If they shoot at Palestinians, they never even ask about them or pursue them.”

Israeli police declined to respond to several requests for information on specific cases. But spokesman Mickey Rosenfeld said coordination with Palestinian police is strong and that authorities go after all criminals, regardless of ethnicity. “The law is the law,” he said.