The defendants were sentenced to death by hanging on Monday, over the deadly abuse against Ahmed al-Kheir at an intelligence services facility in the eastern state of Kassala.
The 36-year-old teacher died in early February two days after being arrested for taking part in weeks of protests against the rule of longtime president Omar al-Bashir.
According to his family, security officials initially claimed he had died of poisoning, though days later, a state investigation found he had died of injuries from beating.
Another protester dies while celebrating court ruling
The ruling was welcomed by hundreds of people who gathered outside the court in Omdurman, where the verdict was delivered.
People were celebrating the ruling outside the court when security forces fired tear gas and caused the death of a woman who suffered from asthma, doctors said.
The trial, which is the first to deliver sentences over the crackdown on this year’s protests, restored confidence in the judiciary, the Sudanese Professionals Association (SPA) said.
“With this ruling, the revolution will have paid off its debt to the martyrs a first time, to be followed as many times as the number of martyrs,” it said.
Thirteen people were also sentenced to prison terms and a further four were acquitted in the ruling, which could face several stages of appeal.
At least 170 people were killed during a crackdown against demonstrations, which eventually led to the ouster of Bashir in April — 30 years after he took power in a coup.
Earlier this month, a court sentenced Bashir to two years in prison for corruption and the illicit possession of sizeable amounts of foreign currency.
Sudan’s ex-president Bashir gets two years’ detention for corruption, hoarding foreign currencyA Sudanese court sentences former president Bashir to two years in confinement for corruption and illicit possession of foreign currency.
The African country is now run by a transitional government, composed of military rulers as well as members of the protest movement.
Sudan has also opened an investigation into war crimes committed by the former leader and his regime in the Darfur region.
The conflict between pro-government forces and ethnic minority rebels, which began in 2003, left around 300,000 people dead and 2.5 million displaced, according to the United Nations (UN).
Ten years ago, the International Criminal Court issued an arrest warrant for Bashir on charges of genocide, war crimes, and crimes against humanity. He has not been extradited to The Hague, though.
Sudan, rebels agree on Darfur de-escalation roadmapThe Sudanese government and nine rebel groups sign an agreement on a roadmap towards ending the bloody conflict in the Darfur region.
The transitional government, led by Prime Minister Abdalla Hamdok, has been engaged in talks with rebel groups to reach a peace deal to end the wars in Darfur, Blue Nile, and South Kordofan.
Sudan deploy troops to West Darfur
Meanwhile, deadly violence broke out around West Darfur’s regional capital, al-Geneina, on Monday, which prompted the Sudanese authorities to announce plans to deploy troops to the region.
Officials also said peace talks with the groups would be suspended for 24 hours, without providing the details about the scale of the deployment or the clashes around the city.
But according to Information Minister Faisal Saleh, authorities will send aircraft to the city to evacuate the wounded to the capital, Khartoum.
There was no information on the number of casualties, either.
The regional government has declared a curfew across West Darfur.