After Hook left a voice message with Israeli authorities that Palestinian militants ("shabab"-youth) had "knocked a hole in the wall" and "pinned down" his men, during an engagement in Jenin, he was shot and killed by an Israel Defense Forces sniper.

[1] After being discharged from the British military, Hook began working for the United Nations (UN) as an aid worker, supervising the construction of a hospital in Pristina, Kosovo, in 1999.

[5] On 22 November 2002, Hook left a voice message with Israeli authorities that armed Palestinian militants ("shabab"-youth) had "knocked a hole in the wall" of the UNRWA compound and "pinned down" his men.

[6] During a gun-battle that then ensued with Islamic Jihad militants whom Israel says were firing at troops from inside the UN compound, an Israeli military sniper killed Hook.

[4][12][13] The United Nations stated that there were no gunmen at the compound, and dispute the claims that the shooting was a mistake; Hook was shot in the back by a sniper with a scoped rifle, from a distance of 20 meters.

[18] More than sixty United Nations workers wrote a letter criticizing Israeli troops for "senseless" and "wanton" behavior, complaining of abuse and humiliation.

[7] Israel responded by releasing to newspapers what the New York Times called a "damning intelligence report" saying UNRWA operations were being used as cover for "Palestinian terrorists", including smuggling arms in UN ambulances and hosting meetings of Tanzim in UN buildings.

[19] In 2005, Irish activist Caoimhe Butterly gave written eyewitness testimony in the inquest into the killing of Hook by an Israeli military sniper.