It has been two years since Egyptian security forces killed up to 1,000 supporters of ousted Islamist president Mohamed Morsi in Midan Rabaa al-Adawiyya, a public square in eastern Cairo. Members of the Muslim Brotherhood and their allies had occupied the square for 47 days when security forces attacked at 6 a.m. on Aug. 14, 2013. Human Rights Watch has described what followed as “one of the world’s largest killings of demonstrators in a single day in recent history.”

Those events have been the subject of two independent investigations by Human Rights Watch and the Egyptian Initiative for Personal Rights. Both concluded that Egyptian security forces launched an all-out assault on predominantly unarmed protesters. A third investigation, by the state-affiliated National Council for Human Rights, exonerated the post-Morsi government and claimed that unidentified armed assailants among the protesters provoked the violent response from the security forces.

Such reporting by human rights groups has focused on the legality or otherwise of the Egyptian military regime’s use of force. By comparison, relatively little is known about the socioeconomic profiles of those who joined the occupation. In a tragic irony, the manner in which the killing unfolded allows us to address this shortcoming. Because security forces fired indiscriminately into the crowd, the victims were effectively a random sample that can help us better understand the social backgrounds of pro-Morsi protesters in the square.

To conduct our analysis, we identified the home districts of 701 protesters killed at Rabaa using biographical data collated by WikiThawra, an online database of protesters killed and arrested in Egypt since the January 25th revolution. We then measured how the fatality rate varied across 333 districts, the lowest administrative level for which census and electoral data is available.

The victims came from more than half of the country’s districts. Surprisingly, the fatality rate was not higher in districts that had voted for Morsi in the first round of the 2012 presidential election. However, two variables are significant: a district’s distance from Cairo and its illiteracy rate. The first graph shows the actual relationship between these two variables and the number of people killed. It also plots the statistical relationship. Note that we also adjust for the presence of parallel pro-Morsi occupations in other Egyptian cities, which provided alternative venues for protest against the coup.

The second graph focuses on the rate of illiteracy, after taking into account a district’s distance from Cairo and alternative sites for protest. As our analysis shows, pro-Morsi protesters killed at Rabaa came from districts with low rates of illiteracy, in other words the most prosperous and urbanized parts of the country.

This finding is important because it contradicts much of the reporting by state and pro-military private media in Egypt, which routinely depicts the Rabaa protesters as either “half-educated,” or “peasants”  bused in from the countryside. Another version of this narrative asserts that, “75 percent of those in Rabaa were poor, lured into joining the occupation by the promise of a free meal.” Such labels play on enduring class cleavages in Egyptian society, and are designed to delegitimize popular opposition to Morsi’s ousting.

Of course, whether or not protesters killed at Rabaa came from relatively prosperous urban areas does not alter the culpability of the current military regime. What it does do is further expose the energetic and politically motivated myth-making that has been taking place in Egypt since the crackdown began.

Neil Ketchley is the Hulme Postdoctoral Research Fellow at Brasenose College, University of Oxford. Michael Biggs is an associate professor of sociology and a fellow of St Cross College, University of Oxford. Their latest working paper, which was supported by a TRE Grant from the Project on Middle East Political Science, explores the social contexts of Islamist activism in Egypt.