The migrant who killed one person and injured six others in a knife attack in a Hamburg supermarket was a radicalized Islamist known to German security agencies, but also believed to have psychological problems.

Officials said on Saturday the agencies had believed he posed no immediate threat.

A security lapse in a second deadly militant attack in less than a year, and two months before the general election, would be highly embarrassing for German intelligence, especially since security is a main theme in the Sept. 24 vote.

A Tunisian failed asylum seeker killed 12 people by driving a truck into a Christmas market in Berlin in December, slipping through the net after intelligence officers who had monitored him reached the conclusion he was no threat.