Story highlights The gunman told an 18-year-old he won't kill him if he gives police an envelope

But the teen was also forced to watch his classmates and teacher get killed

(CNN) The killer called him "the lucky one."

For reasons he might never understand, Matthew was chosen to live by the gunman in last week's Oregon community college shooting that left nine people dead.

But the 18-year-old had to perform two tasks to save his life: deliver the gunman's message to police, and watch his classmates get shot right in front of him.

Photos: Shooting at Oregon community college Photos: Shooting at Oregon community college Community members attend a candlelight vigil at Stewart Park for those killed during a shooting at Umpqua Community College in Roseburg, Oregon, on Thursday, October 1. The massacre left nine people dead and nine wounded. The gunman also died. Hide Caption 1 of 15 Photos: Shooting at Oregon community college In response to the shooting on October 1, President Barack Obama delivers the 15th statement of his presidency addressing gun violence. "Somehow this has become routine," he said. "The reporting is routine. My response here at this podium ends up being routine, the conversation in the aftermath of it. We've become numb to this." Hide Caption 2 of 15 Photos: Shooting at Oregon community college Students and faculty are reunited with friends and family at the county fairgrounds on October 1. Hide Caption 3 of 15 Photos: Shooting at Oregon community college People wait for information at the fairgrounds on October 1. Hide Caption 4 of 15 Photos: Shooting at Oregon community college Hannah Miles, center, is reunited with her sister Hailey and father, Gary, on October 1. Hide Caption 5 of 15 Photos: Shooting at Oregon community college A student waits to walk off a school bus at the fairgrounds on October 1. Hide Caption 6 of 15 Photos: Shooting at Oregon community college Friends and family are reunited on October 1. Hide Caption 7 of 15 Photos: Shooting at Oregon community college A woman is comforted after the deadly shooting at Umpqua Community College in Roseburg, Oregon, on October 1. Douglas County Sheriff John Hanlin announced at a news conference that the shooter was dead. Hide Caption 8 of 15 Photos: Shooting at Oregon community college Authorities secure the campus after the shooting on October 1. Hide Caption 9 of 15 Photos: Shooting at Oregon community college Students, staff and faculty leave the school on October 1. Hide Caption 10 of 15 Photos: Shooting at Oregon community college A bullet casing is marked at the scene of the shooting on October 1. Hide Caption 11 of 15 Photos: Shooting at Oregon community college People gather at a roadblock near the entrance to the college on October 1. Hide Caption 12 of 15 Photos: Shooting at Oregon community college Authorities respond after reports of the shooting on October 1. Hide Caption 13 of 15 Photos: Shooting at Oregon community college Police search students outside the school on October 1. Hide Caption 14 of 15 Photos: Shooting at Oregon community college A patient is wheeled into the emergency room at Mercy Medical Center in Roseburg on October 1. Hide Caption 15 of 15

The trauma, Matthew's mother said, has been overwhelming.

"He's different," Summer Smith said. "He'll never feel the same. He'll never feel complete security again."