New Delhi, Sept. 21 -- The memorial service for conservative activist Charlie Kirk, who was shot dead on September 10 in Utah, is scheduled for Sunday morning at State Farm Stadium in Glendale, Arizona. Investigators had found a gun near the crime scene within hours, but tracing it proved challenging. The German-made rifle, a Mauser Model 98, is decades old and was originally made for military use in both World Wars. Experts say it likely arrived in the US long before laws in the 1960s required guns to have serial numbers or other marks to allow tracing. Millions of such weapons are still found in homes across the country.

The rifle belonged to the suspect's grandfather, though authorities have not explained how he acquired it. The bolt-...