Ketel Thorstenson, LLP is the region's largest and oldest public accounting and consulting firm. With over 100 accounting pro ... fessionals and four locations, KTLLP is the leader in the Black Hills and beyond. Serving the community since 1936, KTTLP has a depth of knowledge and experience that clients rely on and trust. The KTLLP team takes the time to get to know you and your business well, to offer the best service possible. We live our motto, Friends for Life. read more