The Egyptian government's assertion that an Italian Cambridge University student was killed by a gang have been branded "implausible" by UK academics.
The body of Giulio Regeni, which showed clear signs of torture, was dumped beside a road near Cairo on 3 February.
Egypt's interior ministry said on Thursday that police had found his bag in a flat linked to members of a criminal gang killed in a shoot-out.
The UK academics called for an inquiry into Mr Regeni's death.
The 28-year-old Italian student had been researching trade unions, a politically sensitive subject in Egypt.
Human rights groups and opposition figures have speculated that he was killed by members of the Egyptian security forces - claims Egyptian officials have strongly denied.
Dr Andrea Teti, senior lecturer at the University of Aberdeen, said the official claim that Mr Regeni had been murdered by a criminal gang was the "latest and greatest implausible statement in a long line of risible official positions".
Dr John Chalcraft, associate professor from the Department of Government at the London School of Economics, said: "The allegation that a criminal gang abducted, tortured and killed Giulio is inherently implausible and unlikely.
"The threat of criminal gangs targeting foreigners has not registered in any university risk assessments in regard to researchers in Cairo, as far as I am aware."
Professor William Brown, Emeritus Master of Darwin College, who worked with Mr Regeni, is one of six Cambridge University lecturers who have written to the Egyptian embassy in London demanding answers.
He said: "The more that emerges around the circumstances of Giulio's death, the greater the need for an independent enquiry.
"This matters both for Egypt's international reputation and for the future safety of academics and students who work there."
The BBC has approached the Egyptian government for comment but has not received a response.