Born in Chicago, Illinois in 1956, Mark moved with his family in 1961 to Prairie Village, Kansas, where he grew up.  He is the fourth of nine children (six girls and three boys), the son of Tom and Mary Mertes.  He attended parochial school at St. Ann in Prairie Village, then Rockhurst High School, and the University of Kansas, graduating in 1978 with a degree in Business Administration.

Mark entered the Peace Corps in 1978 and served with an Immunization Project in the Yemen Arab Republic for 18 months.  After a period of working for J. C. Penny, Mark entered St. Meinrad Seminary, and graduated with a Masters of Divinity in 1987.

His priesthood assignments have included Associate pastor at Holy Spirit in Overland Park, Associate pastor at the Cathedral of St. Peter, Chaplain at Ward High School, Archdiocesan Liason for Charismatic Renewal, Pastor at St. Joseph, Olpe and St. Mary, Hartford, and since 1998, Pastor here at Holy Cross.