Osama Suleiman spends almost all his waking hours next to a laptop and a pile of cellphones in his apartment in Coventry, England, up the road from the family-owned clothing store.
He fields calls from some 230 activists inside Syria, who report on what they hear and see of clashes, deaths and violence. Mr. Suleiman, who set up the Syrian Observatory for Human Rights seven years ago, then consolidates the data and publicizes casualty figures.
But a correct body count in this war, as in many others, is not an exact science, and is subject to dispute and fraught with emotion. The Observatory's casualty count is consistently lower than those assembled by the United Nations and its agencies – sometimes by as much as 30 per cent. But for Mr. Suleiman, who often uses the pseudonym Rami Abdul-Rahman, accuracy is key to credibility for people like him who oppose the regime of President Bashar al-Assad. "You don't help your case if you're not factual," he said.
Death tolls for Syria are important because governments depend on casualty figures to weigh policy positions and to assess grounds for military intervention and humanitarian aid assistance. But shifting battle zones and government restrictions have curbed any ability to count accurately.
From a tiny bedroom-turned-office in his apartment, Mr. Suleiman, 42, said he is in constant communication with people in Syria who report to him over expensive satellite phones or cellphones belonging to people who have already died "so the regime can't track us."
Not everyone agrees with his figures. Benetech, a California data-analysis company hired by the United Nations, concluded that 59,648 people had died in the Syrian conflict through last November. Mr. Suleiman vigorously rejects that figure, saying his network of activists in all 14 Syrian provinces is more reliable. For the same period, he estimated around 36,000 casualties.
At the end of February, he concluded that the escalating conflict had so far cost around 55,000 lives. The UN High Commissioner for Human Rights gave another figure last month, 70,000.
Benetech relied on data-mining and math to classify records. "This is the most accurate number of documented, identifiable killings in Syria between March, 2011, and November, 2012," said Megan Price, a co-author of the Benetech report.
The data sets were sourced from six different Syrian opposition groups and the Syrian government, all groups, like Mr. Suleiman's, with vested interests in the conflict's outcome.
There is no single best way to count war dead, , said Debarati Guhu-Sapir, director of the Centre for Research on the Epidemiology of Disasters in Belgium.
"Very good statistical techniques exist, but the motivation behind counting the dead should be considered," she said. "The numbers coming out of Syria are almost all advocacy estimates."
Mr. Suleiman said the UN is "politicizing" the conflict.
"I had names for over 1,000 people who the UN said are dead but they're alive. They took the names from other groups that miscounted," he said.
"Maybe we have over 100,000 dead," added Mr. Suleiman, "but when you are the UN, a big organization, you have the power to affect change."