GAZA CITY (Ma'an) -- An appeals court in the Gaza Strip on Monday convicted four Palestinians of the killing of Italian peace activist Vittori Arrigoni in 2011.

The court sentenced Mahmoud Salfiti, 23, and Tamer Hasasna, 25, to life imprisonment plus 10 years for kidnap and murder, while Khader Ajram, 26, was sentenced to 10 years for abduction.

The three defendants were identified by the Hamas-run court as Hamas security men who had been working for a Salafi group for ideological reasons.

Amer Abu Ghula, a 25-year-old fisherman, fled Gaza after the killing and was sentenced in absentia to 12 months for harboring a fugitive.

The men flashed defiant smiles as the sentences were handed down.

"They will find justice with God and not with this court," a relative of the one of the defendants muttered.

Lawyers said Arrigoni's family had written to the court to oppose imposing the death penalty.

Hamas forces killed two men accused of the murder when clashes erupted during a raid in Nuseirat refugee camp three days after Arrigoni was killed. A third was injured and a fourth detained.

Arrigoni, a long-time member of the International Solidarity Movement, was kidnapped on April 14, 2011.

Shortly after his disappearance, a previously unknown Salafist group released a YouTube video showing a bruised and bloodied Arrigoni and threatened to kill him within 30 hours if Hamas failed to release a group of jihadist prisoners.

Security forces found Arrigoni's body shortly afterward, ahead of the stated deadline, in an abandoned house in northern Gaza.

News of the Italian activist's murder was greeted with widespread condemnation, and demonstrations and vigils were held across the West Bank and Gaza in his memory.