Jeffrey grew up in Lompoc, CA with a many siblings, older and younger. He attended the Pacific Conservatory of the Performing Arts in Santa Maria in Central California, and the Professional Actor's Training Program at the University of Washington in Seattle.

Jeffrey moved to Los Angeles in 1980 where he still lives with his family. Jeffrey is best-known in television for his characters Weyoun and Brunt on "Star Trek: Deep Space Nine." Recently Jeffrey has added the new character Shran on "Star Trek: Enterprise" to his impressive list of Star Trek characters. Besides television, Jeffrey has performed in countless stage plays.