The Honorable J. Mark Costine graduated from St. Clairsville High School and attended Wake Forrest University. He received his Juris Doctorate Degree in 1979 from Ohio Northern University.

The Honorable J. Mark Costine began his term as Probate and Juvenile Judge on December 24, 1998. Judge Costine was a practicing attorney in The Costine Law Firm from 1979 - 1998, and was a Belmont County Assistant Public Defender from 1979 - 1998.

As a student, Judge Costine was a National Finalist in the Reader's Digest Public Speaking Contest. He traveled to Russia to study Russian history and traveled to Jamaica to study world religions. As an Eagle Scout, he participated in various Boy Scout events including the 1971 World Jamboree in Japan, and various high adventure excursions.

Judge Costine is active in the following community and social organizations: Past President of St. Clairsville Rotary, Past President of the St. Clairsville Jaycees, Former Chairman of the Administrative Board of Thoburn United Methodist Church, Former Chairman of St. Clairsville Board of Zoning Appeals, Former Chairman of the St. Clairsville Civil Service Commission, Former Hearing Officer for the Belmont County Fair Housing Commission, Past-President of Belmont Hills Country Club, and Past-President of Belmont County Bar Association.

Judge Costine has also been very active with the youth in the community. He is a Boy Scout Leader and member of the Executive Committee for the Ohio River Valley Council of the Boy Scouts of America. He has been the Coach for the World Finalist Olympics of the Mind Team for two years.

Judge Costine is married to the former Brenda Edler and together, they have three children.