A Munich court on Monday opened proceedings against 32-year-old Philipp K, who the prosecution alleged supplied the weapon used in a deadly rampage at Munich's Olympia mall last year.

The accused faces nine charges of involuntary manslaughter. Philipp K. admitted all charges of illegal arms sales, including the sale of a Glock 17 gun and 450 rounds of ammunition to Munich attacker David S.

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David S., a 17-year-old Nazi sympathizer who suffered from mental illness, is believed to have acquired the weapon from Philipp K. after the two made contact over the darknet. They then met up in the central German town of Marburg where they made the exchange.

In his opening statement, Philipp K. expressed his condolences to the relatives of the victims and explained that, had he known David S. was mentally ill and intended to "commit such an atrocious act," he would have never sold him the weapon.

The prosecution will seek to prove, however, that Philipp K. did know of the teenager's murderous intentions. Chief prosecutor Florian Weinzierl said in his statement that, by supplying the weapon, the accused had empowered David S. to carry out his long-planned rampage.

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Philipp K. was detained in August 2016, days after David S. killed nine people and injured 16 at the Olympia Mall, before killing himself. Investigators tracked him down after tracing further darknet weapons sales. Aside from selling the weapon to David S., he also faces charges of violating Germany's Military Weapons Control Act, which prohibits the sale of military-grade weapons.

The trial is scheduled to span 10 hearings lasting until September 19.

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dm/rt (dpa, AFP)