Iranian officials claimed on Wednesday that they had arrested a person believed to have taken video footage of the final moments of Ukrainian International Airlines (UIA) Flight 752, which appeared to show it aflame before crashing.

The video challenged Iran’s initial explanation for the plane crashing shortly after departing Tehran’s international airport – mechanical failure – particularly compared to the speculation Iran ultimately admitted to, that the Iranian military used a surface-to-air missile to shoot it out of the sky. The sky is largely dark, with a small speck in the distance that appears to be the plane. A projectile clearly hits the speck that creates an explosion, giving the impression that a missile or other weapon targeted it. The video appeared online before Iran admitted to shooting down the plane and after an Iranian “preliminary report” had blamed a spontaneous engine fire for the deaths.

The civilian airliner was flying to Kyiv last week when, shortly after takeoff, it appeared to catch fire and ultimately crashed, killing 172 people on board. Most of the victims were Iranian, Canadian, and Ukrainian citizens. Ukrainian President Volodymyr Zelensky has demanded financial compensation from Iran for the killings.

The BBC cited Iranian media on Tuesday reporting that the Islamic Revolutionary Guard Corps (IRGC), a U.S.-designated terrorist organization, had arrested a person for posting a video taken of the flight burning in air. Fox News corroborated the report, stating that Iranian outlets expected the imprisoned person to face “national security” charges for allegedly filming the video.

Internet security activist Nariman Gharib initially posted the video online.

The footage i've got from a source – the moment the missile hit the #Flight752. I can't verify the video yet! but please let me know if you find anything. I'm in contact with the person who send this video to see if I can get a version of video which has a meta data on it pic.twitter.com/HtesW5uecB — Nariman (@NarimanGharib) January 9, 2020

Gharib told Canada’s CBC broadcaster on Wednesday that he had received threats for publishing the video. He also insisted that his source had not been arrested and that he had confirmed the source’s freedom Wednesday morning, after reports of the arrest surfaced. He left open the possibility that Iranian authorities arrested the wrong person for sharing the video.

“The person who is the source of the video is SAFE and I can assure you IRGC is orchestrating another lie,” Gharib said on Twitter. He also urged Canadian Prime Minister Justin Trudeau to intervene on behalf of the person arrested, if anyone, and have them released.

The alleged videographer behind the short film is the only person at press time that Iranian authorities have specified that they arrested. The deputy head of the Iranian judiciary, Hadi Sadeqi, reportedly announced “arrests” on Tuesday in relation to the attack on Flight 752, but did not name the individuals or identify them in any way, including offering any estimate as to how many people were in custody over the incident.

Despite publicly accepting “human error” as the cause of the plane crashing on Saturday, Iranian authorities have continued to blame the United States, despite no evidence of any American military or civilian activity in Tehran that day in relation to the flight. Senior officials speculated on Wednesday that American “cyberattacks” could have resulted in the IRGC shooting at least one missile at the civilian airliner, or that “enemy sabotage” through infiltrating the IRGC and shooting down the plane to embarrass Tehran was possible. No officials have offered any evidence to substantiate this allegation.

Iranian President Hassan Rouhani also formally blamed America for Iran killing 176 civilians in remarks Tuesday.

“It was the US that caused such an incident to take place,” he asserted, claiming that, without the U.S. military conducting an airstrike against Iranian terror chief Major General Qasem Soleimani, Iranian soldiers would not have attacked the Ukrainian airliner. President Donald Trump has repeatedly asserted that Soleimani, responsible for hundreds of American deaths and thousands wounded, was planning an imminent attack against Americans at the time of the airstrike.

An Iranian General Army Staff statement made a similar argument.

“Following the threats from the president and the military commanders of the criminal US that a large number of targets on the Islamic Republic of Iran’s soil would be hit in case of a retaliatory operation, and considering an unprecedented increase in the aerial movements over the region, the Islamic Republic of Iran’s Armed Forces were on the highest level of readiness in order to respond to possible threats,” the statement insisted, according to Iran’s Tasnim news agency.

At least 1,000 Iranians – the number state-run Fars News Agency admitted to – took the streets Monday to protest their regime for killing dozens of Iranians on the flight. As of Wednesday, video evidence of continued protests against the regime, considered the world’s most prolific state sponsor of terrorism, have continued on college campuses in Tehran. Videos leaking out of Tehran, where the regime strictly regulates the internet, showed tear gas attacks on protesters and at least one protester, a young woman, bleeding profusely from the leg of what appeared to be a gunshot wound.

Follow Frances Martel on Facebook and Twitter.