Abdurrahman sees the competing allegations as evidence that's he's being fair; "You know you're doing a good job when all the sides start to attack you," he said in a recent interview.
Still, one prominent critic says it boggles the mind that a man living in Coventry is somehow able to count and categorise the dead in Syria hour by hour, every day of the week.
"Something is going on which is quite fishy," said As'ad AbuKhalil, a professor of Middle Eastern politics at California State University Stanislaus.
Abdurrahman was working on four hours' sleep when he met The Associated Press at Coventry's drab-looking train station earlier this month.
He'd planned to get to bed by 10pm the previous night, but rebel infighting in the Syrian border town of Azaz meant he stayed up until 2am monitoring developments. He got up again at 6am to check for overnight updates.
"It's not a nine-to-five job," Rami said as he drove across the city, a white dove-shaped air freshener dangling from his rear-view mirror.
By his own account, Abdurrahman operates as a kind of human switchboard, fielding calls round-the-clock from Syrian activists, international journalists, and human rights workers. Particularly intense news days had seen up to 500 calls, he said.
Suspicions have long dogged Abdurrahman. Is the self-exiled Syrian really who he says he is? Who's behind his organisation? And is he accurate enough to justify the world's reliance on his reporting?
Switching from English to Arabic and often speaking through a translator, Abdurrahman - whose real name is Ossama Suleiman - defended his decision to use a pseudonym as part of the Arab tradition of the nom de guerre.
He said he received money from a European human rights group, but declined to name it. Only after prodding did he say he had been receiving less than €100,000 a year since 2012 in support of his work.
"We're in a state of war," he said. "It's difficult to be completely transparent."
Abdurrahman, born in the Syrian city of Banias, says government harassment of his family first sparked his interest in human rights work. He left for Britain in 2000, moving to Coventry, about 160 kilometres northwest of London, where the revenue from the clothes shop helps support him, his wife, and their young child.
He launched the Syrian Observatory for Human Rights in May of 2006, saying the activists he met while in Syria formed the group's core.
Counting the words out with his hand, Abdurrahman said his modus operandi was: "Document, verify, and publish."
That methodology has been put to the test in Syria, where both sides stand accused of peddling misinformation. Abdurrahman said his work was like navigating a "sea of lies".
Abdurrahman boasts 230-odd informants on the ground, ranging from Syrian journalists who leak him stories on the sly to employees of military hospitals who fill him in on army casualties. He said he sticks to the journalistic gold standard of only accepting a story once it had been confirmed by a second source.
He claims to have rarely gotten it wrong, saying he could think of only two cases in which he overstated casualty figures. Other mistakes, such as confusing a car bombing with a mortar strike, were more common, but in every case he insisted errors were corrected.
"We're human, we make mistakes," he said. "But it's our intention not to repeat them."
Abdurrahman's accuracy matters because so many news organisations use his reporting. A review of stories published by three major newswires, including The Associated Press, over the past year show he's cited more often than SANA, Syria's government-run news agency.
Experts attribute the exposure to Abdurrahman's non-stop publication schedule, and the fact that so many observers are barred from Syria and that others are at risk of kidnapping or worse. That means journalists, human rights groups, and even the United Nations - which put out its own death toll at more than 100,000 back in July - have to rely at least in part on his figures.
That level of prominence worries those who harbour doubts about his organisation.
"Let's assume good faith," said Nadim Shehadi, with London's Chatham House think tank. "Let's assume he's genuine, and qualified, and everything. He relies on too many sources to be able to check."
The problem with checking what's going on in Syria is that few people can gain access to the areas involved, said human rights researcher Cilina Nasser, who has collaborated with Abdurrahman in compiling casualty figures on several mass killings.
Nasser, who works for London-based Amnesty International, described Abdurrahman as careful and "usually accurate".
Her opinion was largely seconded by Lama Fakih, a researcher with New York-based Human Rights Watch.
"In broad strokes, the reporting is solid," she said.
Nasser said it was important to keep in mind that everyone - from Abdurrahman to the journalists charged with following up on his figures - labours under the same handicap.
"There's always something missing," she said, "which is us being on the ground."
- AP
