In Walker v. Pennsylvania Board of Probation and Parole, 729 A.2d 634 (Pa. Cmwlth. 1999), the parolee was released in Pennsylvania on parole from charges in the Commonwealth, but was arrested in Maryland on charges of battery, assault and reckless endangerment of another person. He posted bail and was released on the condition that he appear at a hearing in Maryland several months later. The Pennsylvania Board declared him delinquent on parole and detained him pursuant to a warrant for his arrest. He was recommitted as a technical parole violator at the state correctional facility to serve 18 months backtime. Eventually, Maryland obtained custody of him; he was taken back to Maryland for a hearing on his criminal charges; and he was convicted to serve five years with credit for all the time served since his arrest. He was returned to Pennsylvania, and the Board recommitted him as a convicted parole violator and recalculated his maximum sentence date without giving him credit for time served on his Maryland sentence. Noting that Section 21.1(a) of the Parole Act prohibited prisoners from serving sentences concurrently until their original sentence had been served, this Court, nonetheless, held that Walker was entitled to credit against his original sentence of his time served based on the provisions of the United States Constitution to give full faith and credit to a judgment or judicial decree of a sister state.