This work involves model-based identification of rotor crack. A Laval rotor with a transverse surface crack and disc unbalance is studied. Viscous damping, disc eccentricity and additive stiffness due to crack are the parameters considered for identification. The linear system equations of motion together with the switching crack excitation function are used for developing the identification algorithm. Furthermore, the algorithm is extended for a novel attempt of estimating the coefficients of switching crack excitation function, which constitute the crack excitation force. This estimation could be used to provide valuable information on the actual opening/closing profile of the switching crack. The proposed algorithms are illustrated through numerical examples. They are tested against measurement noise and found to be reasonably robust.