A Palestinian Authority Arab asylum-seeker who killed one person and wounded six others in a stabbing attack in a Hamburg supermarket last July has been sentenced to life in prison, a spokesman for a city court said today, reports Reuters . Ahmad Alhaw, 27, went on a stabbing spree killing one and injuring six others, before being overpowered by passers-by who threw chairs and other objects at him, assisting in his arrest, but not early enough to save a 50-year-old man who died of his injuries. The asylum-seeker "could not be deported" as he lacked identification documents and was "psychologically unstable", Hamburg’s Interior Minister Andy Grote said after the attack. The attacker was known to authorities . Grote said he had been registered in intelligence systems as an "Islamist" - "but not a violent one" - as there was no evidence to link him to an imminent attack, Reuters said. Investigators did not find evidence to suggest he was a member of ISIS. The incident was not treated as a terrorist attack. In delivering the sentencing, the judge noted the "particular severity" of the crime, lowering his chances of obtaining early release on parole, reports i24 News . Germany often grants parole after 15 years. Prosecutors said the attack stemmed from a "radical Islamist" motive, charging that the man had hoped "he would die as a martyr". His aim was to kill as many German Christians as possible to avenge Muslim suffering worldwide, they said. Having been rejected for asylum in Norway, Sweden, and Spain, he arrived in Germany in 2015 and was moved to a Hamburg migrant accommodation center, which after July's attack was raided by police. A study commissioned by the German government using data from Lower Saxony concludes that migrants "may be responsible" for most of Germany's recent rise in violent crime , reported the BBC . More than 90% of the increase was attributed to young male migrants.