Cairo, Egypt (CNN) -- A patchwork of blood-red welts and purple bruises cover Ramy Essam's back, from his neck down to his thighs. His scars are evidence, he said, that violent groups linked to ousted Egyptian President Hosni Mubarak's regime are trying to subvert the revolution.
"There are still some people from the corrupt old regime trying to crush the revolution," Essam said, lying face down on his bed, where he has spent days waiting for his wounds to heal. "With God's will, the revolution will continue."
The 23-year-old student and musician said thugs attacked him and hundreds of others at a peaceful sit-in at Tahrir Square on March 9. Egyptian soldiers were on guard but they didn't come to his rescue. Instead, Essam said, they detained him and scores of others and hauled him to the nearby Egyptian museum where uniformed soldiers tortured him for four hours and cut off his shoulder-length hair.
"It was pain I never imagined I would feel in my life," Essam said.
"They took off my clothes. They used sticks, metal rods, wires, whips." He received electric shocks, he said.
"There was a soldier who would jump in the air and land on my face with his legs."
Essam is convinced he and others were marked men and women at Tahrir Square that day. For weeks, Essam had sung and played his guitar for large crowds celebrating the end of the Mubarak regime. Moments before he was detained, several men pointed him out to soldiers, he said.
Essam was released, but human rights groups have said more than 100 innocent activists -- all detained on March 9 -- are still in custody awaiting military trials without access to lawyers. Their stories are almost identical to those of protesters who claim they did nothing wrong, but were illegally detained and often beaten by thugs and soldiers.
"It's disgusting. It's inhumane," said Cairo based human rights lawyer Ragia Omran. "Basically, there were plainclothes thugs or informers who were pointing out to the military the people who come to Tahrir Square, and that's how people got picked up."
In a joint statement released this week, nine Egyptian human rights groups said, "The crime is still going on and the perpetrators deserve a harsher punishment. The junta owes the Egyptian people an apology as they are ruling for the moment."
It's impossible to verify who is behind the violence on March 9. Many suspect remnants from the Mubarak regime with links to rogue factions within the Egyptian military.
The events of that day, and other accounts of violence involving soldiers, are fueling doubts about the Egyptian armed forces, the same institution promising a peaceful changeover to democracy.
Presidential candidate Amr Moussa has said shadowy elements have also fueled recent violence between Egyptian Christians and Muslims. The army has denied the allegations of torture and abuse, and it said anyone in custody is either suspected or accused of breaking the law.
Despite the torture he claimed he suffered at the hands of soldiers, Essam said he still has faith in the army's promise of democracy, but his scars are a reminder that the fight for lasting change in Egypt is not over.
Journalists Dina Amer and Mohamed Fadel Fahmy contributed to this report.