Video report by ITV News Security Editor Rohit Kachroo
Hasnat Karim was with his wife and two children in the Holey Artisan Bakery attack in Bangladesh when an Islamic State siege took place.
The British citizen said he was there for the love of his daughter who was celebrating her 13th birthday that day.
But he has since been arrested and held without charge for six weeks on suspicion of being a former member of an extremist group and an aid to the gunmen who killed more than 20 hostages.
Speaking to ITV News, his wife Sharmina Parveen said he is in fact a hero whose attempts to end the 12-hour stand-off on July 1 has led to the most serious accusations.
Reliving that night, she said: "They were killing the foreigners, they were chopping and we could hear the sound. It was really very scary and at that time I was really worried about my children."
She said her husband was completely innocent, adding: "No-one would take his family with him if he was actually involved with the gunmen."
But Bangladeshi police are investigating him because of images of him talking to the terrorists during the siege.
Nadeem Qadir of the Bangladesh High Commission said: "If you are threatened with your life, especially with your children and wife, you would be trembling, you would be worried. But he is so relaxed."
Hostages from Italy, Japan, America and India were killed in the siege alongside two Bangladeshi police.