Mark's sister last saw him on Saturday evening, September 30, 2006. Mark had worked his shift at Walmart, arrived home at around 11:15pm, had a snack, asked his sister to wake him at 8:00 the following morning and went to bed. On Sunday morning, around 6am, his sister was awakened by the state police, who told her that Mark's truck was parked on the Shenango River Bridge on the Rte 422 Bypass in Taylor Township. The keys were in the truck. She checked Mark's room, discovered that he was not in the home and drove out to where his truck was parked. A search was initiated at 6:30 that morning, with local police and the Taylor Township Fire Department searching the area where the truck was found. A state police helicopter flew over the river but no sign of Mark was found. Mark previously lived in Slippery Rock but moved in with his sister in their late father's house in Princeton after their father's passing 5 months prior to Mark's disappearance. Whether Mark jumped from the bridge or walked away has never been determined.