The Afghan youth who was arrested on Sunday was in contact over WhatsApp with the 18-year-old gunman who killed nine people at a Munich shopping mall, authorities said on Friday.

The 16-year-old attempted to delete the chat thread between himself and the German-Iranian shooter, but police were able to retrieve the messages.

"This (WhatsApp) chat and questioning as a suspect has shown that the Afghan met the gunman directly before the gun attack at what was later the scene of the crime," Bavarian senior public prosecutor Thomas Steinkraus-Koch said during a news conference in Munich.

Chats between the two showed that the Afghan teen knew that the attacker had a Glock 17 firearm, Steinkraus-Koch said. The pair also met shortly before the shooting at the Olympia shopping mall, leading the prosecutor to believe that "he could have known something about the act."

The Afghan youth will now be brought before a judge on suspicion of "failure to report a crime."

Investigators also revealed that the two teens met each other while undergoing psychiatric care. The two shared a passion for first-person shooter games and discussed mass shootings.

During their time in the psychiatric ward, the Afghan learned that the shooter, known as Ali David S., had "a hatred for people" and idolized Norwegian mass murderer Anders Behring Breivik, said authorities.

The shooting in Munich on Friday took place on the five-year anniversary of the Breivik massacre in Norway. The white supremacist killed 77 people on July 22 in 2011 and a copy of his manifesto was found on the German-Iranian teen's computer.

The Olympia shopping center reopened to the public on Monday, three days after the 18-year-old opened fire, killing nine and wounding 35. None of the injured are in critical condition, authorities said on Monday.

rs/rc (AFP, dpa, Reuters)