BAILEY, Colo. -- The mother of Cassidy Griggs told the Associated Press that her son lied in describing what unfolded in the classroom where Emily Keyes was killed. She said he was not in the class, and the she doesn't know why he lied.

A 16-year-old student at Platte Canyon High School, Cassidy Grigg, initially said in interviews with network morning shows that he was in the classroom that was invaded by the gunman. He said the gunman lined up students by the chalkboard and offered to stay with the girls -- but the gunman threatened to kill him.

His father, Tom Grigg, gave a similar account of what his son had told him to The Associated Press. But Thursday, the teen's mother said he made the entire story up.

Larina Grigg said her son told her he fabricated the story because he wanted it to be true.

"He said, 'Mom, all those kids were my friends and I just wanted so much to help them. ... I guess I just made it up in my mind. I just wanted it to be true so bad,"' she said.