When Donald Trump, said he would “rescue” protesters if Iranian authorities started shooting, Siavash Shirzad believed the US president.

The 38-year-old father had seen protests rise up before, only to be brutally crushed by authorities.

But this was the first time in his life that the president of the United States had promised to help demonstrators. Reassured, Shirzad took to the streets, ignoring his family’s warnings and joining the growing crowds.

Authorities started shooting, but no help came. On 8 January, the internet was shut off and Iran went dark, Shirzad was shot at a protest in Tehran and died of his wounds hours later, leaving behind a 12-year-old son.

“Siavash hoped until the very end that Trump’s help would arrive,” his cousin said, speaking anonymously for fear of repercussions. “We told him: ‘Don’t go, it’s dangerous.’ But he gave a firm answer: ‘Trump said he supports us, I’m going.’”

On Tuesday, Trump urged Iranians to keep protesting and to “take over your institutions”, telling them “help is on its way”, as reports grew that a strike on Iran was imminent. But just a day later, Trump abruptly did an about-face, telling reporters that he had received assurances that Iranian authorities would not execute anyone, walking back from military intervention in Iran, at least temporarily.

In Iran, protesters despaired. Despite Trump’s reassurances, killings of demonstrators continued.