Hours after an Islamist extremist group announced it had kidnapped an Italian peace activist in the Gaza Strip, the man's body was discovered in the restive seaside territory. It was the first kidnapping of a Westerner in four years and one of the few times such an abduction has ended fatally.

The hostage, Vittorio Arrigoni, a pro-Palestinian activist for the advocacy group the International Solidarity Movement, had appeared blindfolded in an Internet video released by the Tawhid and Jihad group, which threatened to kill him unless its imprisoned leader and two other members of radical groups were freed by Hamas, the Islamist group that controls Gaza.

The group set a deadline of Friday evening, but Arrigoni’s body was found by Hamas police well short of that, Hamas officials said. They said they had arrested two suspects and were searching for a third. Hamas said it "condemns the heinous crime that does not reflect our values, our religion or our custom and tradition," according to an Interior Ministry statement released to Palestinian news media.

But the kidnapping raised questions about Hamas' control over Gaza, and it represents the latest example of how smaller, more radical groups in the territory -– some with alleged ties to Al Qaeda -– are challenging the rule of Hamas, which itself is viewed by Israel and the United States as a terrorist organization.Those groups complain that Hamas has become too moderate.

Hamas, which has ruled Gaza since 2007, has been cracking down on Islamist Salafists over the last 18 months, arresting their members and killing one of their spiritual leaders during an armed clash in August 2009.

Gaza residents said Arrigoni arrived in 2009 aboard a ship challenging the Israeli naval blockade after the 2008-09 Israeli offensive in Gaza known as Operation Cast Lead. His abduction was the first of a foreigner since Hamas took control of the territory. The last foreigner kidnapped here was BBC reporter Alan Johnston, who was abducted in March 2007 and released three months later.