His father, Arlie De Jarnatt, was a teacher and public representative who taught history and civics at Monticello Middle School and later R. A.
Although he was a successful sprinter at high school (where he set several records), he chose Occidental College in Los Angeles, rather than take a track scholarship to a local public university, because he preferred the Southern Californian climate and environment.
In 1983, Miracle Mile was chosen by American Film magazine as one of the ten best unproduced screenplays circulating in Hollywood.
[6] That same year, De Jarnatt received his first screen credit as one of the writers of Strange Brew, a comedy starring Rick Moranis and Dave Thomas as their respective SCTV characters Bob and Doug McKenzie.
De Jarnatt has also directed episodic television, including The X-Files, Lizzie McGuire, Flight 29 Down, ER, and Alfred Hitchcock Presents.