“The Forensic Department of Police Bureau of Investigation has confirmed it,” Brahmanbaria Additional Superintendent of Police Md Iqbal Hossain said on Tuesday.
Investigators cleared Rasraj of the charge after finding no evidence that he had uploaded the image from his mobile phone.
The ASP said although the items seized from Al-Amin Cyber Point and Studio, the suspected origin of the photo, provided no evidence of its involvement, they did still suspect that some evidence might have been removed from there soon after posting.
Rasraj, a fisherman, was arrested for allegedly posting the photo on Facebook. He was later released on bail.
A mob attacked Hindu-dominated localities in Brahmanbaria's Nasirnagar on October 30, injuring more than 100 people and damaging at least 17 temples and over 50 houses over the post. Two days later, six more Hindu houses were set alight in the upazila.
The ruling Awami League had suspended three of its grassroots leaders for their involvement in the incidents.
Fisheries Minister Sayedul Haque on November 5 said Rasraj could not have created the Facebook post as it was unlikely that he could operate the social media site by himself.
ASP Iqbal, quoting locals, said Rasraj was out fishing in the marsh when the image was uploaded.
Rasraj had apologised before the attack, saying his account was hacked.