German police said on Sunday they had arrested a 16-year-old Afghan friend of the gunman who killed nine people in a rampage at a shopping center in Munich on Friday before taking his own life.
“We suspect that this boy aged 16 years could have been aware of the act,” police said in a statement following the shooting spree after which the 18-year-old German-Iranian gunman killed himself.
The arrest is the first in the investigation.
Authorities said Sunday that Ali Sonboly had planned his attack for a least a year.
Bavarian investigator Robert Heimberger said Sonboly visited the site of a previous school shooting in the German town of Winnenden and took photographs last year, then set about planning the attack.
“He had been planning this crime since last summer,” Heimberger told reporters.
There is so far no evidence that he knew any of his victims, or that there was any political motivation behind the attack, said Thomas Steinkraus-Koch, a spokesman for the Munich prosecutors’ office.
Sonboly received both inpatient and outpatient psychiatric treatment last year to help him deal with “fears of contact with others,” Steinkraus-Koch added. He said medication had been found at his home but that investigators needed to talk with his family to determine whether he had been taking it.
Investigators said they saw an “obvious link” between the killings and white supremacist Anders Breivik’s massacre of 77 people in Norway exactly five years earlier.