Naples, August 1 - Three people are being probed in relation to Sunday's bus crash near the southern city of Avellino that killed 38 people. Charges of multiple manslaughter are a possibility, the prosecutor Rosario Cantelmo said. Gennaro Lametta, owner of the bus company and brother of Ciro Lametta, the driver who died in the crash, is under investigation for the vehicle's upkeep and inspection regularity. Two highway employees are being probed for guardrail installation and upkeep. The bus slammed into a protective guardrail before flying off a high viaduct when the barrier gave way. Before crashing into the railing, the bus struck six cars travelling on the highway. The bus had been carrying a group of friends returning from a weekend excursion to the local Telese thermal baths and the popular pilgrimage destination of Pietralcina.