"Initial inspection of the body indicates that (this) was no accident," Ahmed Nagy, the lead Egyptian prosecutor in the case, told CNN. "We suspect it's a criminal act."
Giulio Regeni, 28, was last seen heading to a birthday party on January 25 -- the fifth anniversary of the start of the uprising that ended the 30-year reign of Egyptian President Hosni Mubarak
Residents of Cairo's Hazem Hassan neighborhood found the body with no pants on the side of a road, said Nagy, a prosecutor in South Giza.
"There were bruises all over the body, swelling in the hands, and wounds on the face and head," he said. "There was a small cut on his ear."
Regeni had gone to Cairo to conduct research on Egyptian trade unions for his doctorate at the University of Cambridge, according to his resume.
After he disappeared, some of his friends launched a social media campaign to try to find him, using the hashtag #whereisgiulio.
Authorities managed to identify his body after going through missing persons reports, Nagy said.
"We are waiting for (the) investigation to reveal his movements and what happened to him," the prosecutor added.
Italians want to participate in investigation
"Obviously, we are very upset for what happened, and we asked the Egyptian government to cooperate and to allow the Italian authorities to be involved in the inquiry to understand what happened there," said Italian Foreign Minister Paolo Gentiloni. "It's not acceptable that, if an Italian citizen is a victim -- and in such a way is a victim -- of a tragedy in Cairo, there is no cooperation.
"So I'm confident that the Egyptian authorities will cooperate with us to understand what happened, to establish the truth of what happened," Gentiloni said.
Egyptian President Abdel Fattah el-Sisi
expressed his "sincere condolences" to Italian Prime Minister Matteo Renzi in a phone conversation Thursday afternoon, the Egyptian leader's office said.
El-Sisi vowed that Egyptian authorities will pay "the utmost attention to investigating the incident ... and follow up on all the circumstances surrounding it."
"The (Egyptian) President stressed that the Italian side will find the necessary cooperation by the Egyptian competent authorities in this regard," El-Sisi's office said in its statement.