Baghdad ? An al-Qaida-linked insurgent shot and killed his own father as he slept in his bed Friday for refusing to quit his job as an Iraqi interpreter for the U.S. military, police said, a rare deadly attack on a close family member over allegations of collaborating with the enemy.

The attack happened on a particularly bloody day in Iraq, with at least 27 people killed nationwide in bombings and ambushes largely targeting the houses of government officials, Iraqi security forces and those seen as allied with them.

Hameed al-Daraji, 50, worked as a contractor and translator for the U.S. military for seven years since shortly after the U.S.-led invasion that toppled Saddam Hussein in 2003.

He was shot in the chest about 3 a.m. while sleeping in his house in Samarra, a former insurgent stronghold 60 miles north of Baghdad, police Lt. Emad Muhsin said.

Authorities arrested the son and his cousin, saying the young men apparently were trying to prove their loyalty after rejoining the insurgency. Police were also looking for another son who allegedly took part in the attack.

Citing confessions, police said the son whom they arrested, Abdul-Halim Hameed, 30, was a former member of al-Qaida in Iraq who quit the terror network in mid-2007 under pressure from U.S.-Iraqi security operations that have led to a sharp drop in violence in the area.

Col. Hazim Ali, a senior security official in Samarra, said Hameed, his 19-year-old cousin and 24-year-old brother remained committed to extremist causes.

With U.S. troops withdrawing from the country, Ansar al-Sunnah, an insurgent group with ties to al-Qaida, recently lured the men into their ranks with offers of hard cash, Ali said.

The U.S. military said it was looking into the report.

The Samarra assault brought into focus the fears of Iraqis who have worked with the Americans and are worried they’ll face renewed violence as their employers prepare to leave the country by the end of next year.

Already, many have been targeted by extremist groups who view them as traitors. But Iraqis could not think of another case in which a family member killed an immediate relative because of his or her employment with the Americans in this country.

Such attacks have happened elsewhere, though.

Several suspected collaborators have been killed by relatives in recent years in the Gaza Strip in an attempt to clear the family name. Most recently, three alleged informers for Israel were killed by family members after busting out of Gaza’s central prison during Israel’s military offensive against Gaza in the winter of 2008-2009.

Samarra, in the Sunni heartland north of Baghdad, has been one of the hardest areas to control since the U.S.-led invasion. It was the site of the February 2006 bombing that destroyed a revered golden-domed Shiite mosque, sparking a wave of retaliatory sectarian violence that pushed the country to the brink of civil war.

The area has been relatively peaceful since local tribal leaders revolted against al-Qaida in Iraq, but Ali said sleeper cells were waiting for the chance to regroup.

“Al-Qaida and other terrorist groups are trying to recruit some young people in order to carry out attacks in an apparent attempt to show that they are still active,” Ali said.