An Italian student who went missing in Cairo last month has been found dead, with numerous bruises, cigarette burns and stab wounds on his body — suggesting a "slow death," an Egyptian prosecutor told the Associated Press on Thursday.

Giulio Regeni, a 28-year-old Ph.D. student at the University of Cambridge, was discovered Wednesday alongside a highway near Cairo. His body, which was found naked from the waist down, was identified by his roommate, prosecutor Ahmed Nagi told the AP.

Nagi said that "all of his body, including his face" was covered in wounds, which indicated that Regeni had been tortured.

Regeni went missing in Cairo on Jan. 25 — the fifth anniversary of the revolution to overthrow Egyptian President Hosni Mubarak. A friend told Reuters that Regeni had gone downtown to meet another friend and never returned.

A #whereisgiulio campaign was launched to find Regeni, and Italian authorities began to express growing concern over his disappearance.

Regeni's body was found in a ditch on Cairo-Alexandria Road in the capital's 6 October suburb, according to the AP.

A source familiar with the case told the Associated Press that the body was "partially burned."

Italy's Foreign Ministry called on Egyptian authorities to "immediately" launch a joint investigation into Regeni's death.

The Foreign Ministry said in a statement that Italy wanted "maximum collaboration at all levels in light of the exceptional gravity of what happened," according to BBC News. It added that the Egyptian ambassador had "expressed profound condolences" and "assured us Egypt will cooperate fully in finding those responsible for this criminal act."

According to Regeni's resume, which was obtained by Reuters, he spoke multiple languages and had won several scholarships. His doctoral research was on trade unions in Egypt following the 2011 uprising against Mubarak, Reuters reported.

Regeni was a student in Cambridge's Department of Politics and International Studies and was a visiting scholar at the American University in Cairo, according to BBC News. Both universities released statements on Twitter on Thursday morning, expressing condolences for Regeni's friends and family.

Italy has requested that Regeni's body be returned to the country.