SB 9.9.25
raksasam bhavam apannah
pade kalmasatam gatah
vyavaya-kale dadrse
vanauko-dampati dvijau
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Saudasa thus acquired the propensity of a man-eater and received on his leg a black spot, for which he was known as Kalmasapada. Once King Kalmasapada saw a brahmana couple engaged in sexual intercourse in the forest.