Matthew Dean Karchner, is a former professional baseball player who pitched in the Major Leagues from 1995 to 2000. He was named on December 13, 2007 in the Mitchell Report as having witnessed two Chicago Cubs teammates taking steroids during spring training in 1999. He also told baseball investigator George J. Mitchell that one of the players had injected the steroids into the other player's buttocks, and then injected them into his own body. Karchner would not identify the players. He also declined to identify the names of Cubs teammates whom he said had offered him steroids. Karchner and his wife, Teresa, currently live in his hometown of Berwick, Pennsylvania, with their two children, Emma and Brooks. 

June 28th, 1967 in Berwick (Age 57)