German police have arrested an Afghan youth on suspicion of a connection to the Munich shopping mall shooter who killed nine people.
The 16-year-old was under investigation for possibly having failed to report the plans of the gunman, named locally as Ali David Sonboly, who later shot himself.
“There is a suspicion that the 16-year-old is a possible tacit accomplice to (Friday’s) attack,” it said.
Police earlier said planned his attack for a year and chose his victims at random, investigators have said.
The 18-year-old German-Iranian opened fire at a McDonald’s restaurant at Bavaria’s largest shopping centre on Friday.
Bavarian investigator Robert Heimberger said the shooter visited the site of a previous school shooting in the German town of Winnenden and took photographs last year, then set about planning Friday’s attack, according to Associated Press.
“He had been planning this crime since last summer,” Heimberger told reporters.
Investigators also found on his computer photos of Anders Breivik - who, five years to the day of the Munich attack, slaughtered 77 people. The Munich gunman also used a similar Glock 17 pistol.
The weapon was likely to have been purchased through a website trafficking illegal weapons on the so-called “dark web”, and was a re-activated gun that had been modified to use in theatres.
There is so far no evidence that the shooter knew any of his victims, or that there was any political motivation behind the attack, said Thomas Steinkraus-Koch, of the Munich prosecutors’ office.
The solo shooting spree saw nine people murdered and 27 others injured - 10 of whom are in a critical condition - before he took his own life.
Officials said the killer used a 9mm pistol and had 300 rounds of ammunition in his rucksack when he went on what they called a “classic shooting rampage”.
Police said the weapon was a Glock 17 handgun which had had its serial number illegally filed off, and there were indications the gunman had been in psychiatric care and treated for depression.
They confirmed his room in the flat he was living in had been searched, and that documents of “frenzied attacks” had been discovered, but no evidence he had links to Islamic State.
Police said the gunman had hacked a Facebook account and lured people to the shopping centre with an offer of free food.
The posting, sent from a young woman’s account, urged people to go to the centre at 4pm, saying: “I’ll give you something if you want, but not too expensive.”
At a press conference on Saturday, German Chancellor Angela Merkel said the events are “difficult to bear for everyone” and pledged to “find out the background” of what happened.
She added: “What lies behind the people of Munich is a night of horror - we are still shocked by the pictures and reports of the witnesses.
”Nine people who were going shopping on the Friday evening, or wanted to eat something, they are now dead - it seems according to the investigations, hit and killed by the bullets of one single perpetrator.”
Three of the victims are believed to be from Kosovo, three from Turkey and one from Greece - seven of the dead are understood to be teenagers.