Killion was born in Philadelphia, Pennsylvania and graduated from Cardinal O'Hara High School in 1975.

[1] Killion served as a fraud investigator with the Pennsylvania Department of Revenue and later founded his own pension advisory firm, InR Advisors.

He defeated William Thomas in a special election[3] to succeed former Pennsylvania House Speaker Rep. Matt Ryan, who died of leukemia earlier that year.

[6] Killion has served on multiple boards including for the Children and Adult Disability and Educational Services (CADES), SEPTA, VisitPhilly, the Chester County Chamber of Business & Industry, Southeastern PA Chamber of Commerce and the Southeastern PA Leukemia & Lymphoma Society.

[7] Killion lives in Middletown Township, Delaware County, Pennsylvania with his wife and daughters.