The father of Pavlo Lapshyn, who murdered a Muslim pensioner and planted three bombs at mosques, told ITV News his son had previously detonated a "chemical experiment" at home in Ukraine.
Sergey Lapshyn said: "Well, once, when he was home alone, he did some chemical experiments. It was very hot, and the mix detonated. Of course we got back home immediately and none of our neighbours said anything bad.
"They just asked us not to be so loud. We talked to Pavel it about it and it looked like he stopped experimenting."
Lapshyn's father also added that he had concerns over the case: "I've got a lot of questions. First, I don't believe he killed anyone. I just can't believe this. Second, fascism...he never was involved in politics.
"Okay, he may have been stressed, something clicked and he got certain ideas. But then, why did he try to blow up a mosque, not a synagogue? There's no logic. I've got many questions, and not many answers."