He has shared composer duties with Christopher Lennertz for Supernatural's original music score since Season 1. Typically, they will trade off throughout the season, writing score for about every other episode. He was the key composer who first wrote and introduced the Dean's Family Dedication Theme, which stands with the Silly Brothers Theme as the one of only two motifs to be heard during all three seasons of the show. Analysis of Gruska's Dean Theme motif can be found here. Downloads for all twelve instances of the motif can be found here.