The four young protesters were shot dead in the eastern coastal town as they tried to prevent the flight of Ben Ali's nephew Kais, a day after the leader himself left the country. The victims' relatives have accused security officials of ordering police to shoot at the crowd.
The court also imposed prison sentences of five to 10 years, some in absentia, on several members of security forces over the same incident.
In a separate case, a military prosecutor is seeking the death penalty for the former leader over the killing of at least 22 people in pro-democracy protests in the towns of Thala and Kasserine.
The former Tunisian leader of almost 24 years, Ben Ali already faces countless other charges and has already been sentenced to more than 66 years in prison on a range of charges, including drug trafficking and embezzlement. Ben Ali was toppled by protests which started in December 2010 and led to a moderate Islamist party coming to power in October. His ousting sparked a wave of protests, now known as the Arab Spring that is still causing unrest in the region. He and his wife have been put on the international arrest warrant, but Saudi authorities have been reluctant to respond to Tunisian extradition requests.
