PARIS (AP) — French police investigations into a fatal weekend attack near the Eiffel Tower are looking into the mental health of the suspected assailant who swore allegiance to the Islamic State group before stabbing a German-Filipino tourist to death and injuring two other people with a hammer.

The French national taken into police custody, Armand Rajabpour-Miyandoab, has a history of mental illness and of Islamic radicalization, officials said. He faces a possible preliminary charge of terrorist-related murder for the attack Saturday night that raised fresh questions about security in the French capital before it hosts the Olympic Games next year.

“This is a case that links radical Islam, undeniably, and mental illness. I must tell the French people the truth that there are numerous cases like this,” the interior minister, Gérald Darmanin, said Monday, adding that around one-third of suspected radicals under surveillance have psychiatric issues.

Speaking to broadcaster BFMTV, the minister said French officials should be given greater powers to force people in such cases to seek psychiatric treatment.

“There appears to have been a psychiatric failing because doctors on multiple occasions decided that he was better, that he was more normal and could live freely,” he said.

A few weeks before the attack, the suspect’s mother had told police that her son had stopped taking his medicines, but she was apparently too scared of him to ask that he be hospitalized, the minister said.

“She didn’t want to, apparently because she was scared of her child, which is understandable,” he said. “She came back a few days later to say that he seemed better.”