His maternal grandfather Benjamin Henry Magruder was a prominent Virginia lawyer and legislator, and in 1864, was elected to the US House of Representatives.

After graduating from the Medical College of Virginia in 1888, DeJarnette practiced at the R. E. Lee Camp Confederate Soldiers' Home in Richmond for a year before joining the staff of the Western Lunatic Asylum in Staunton.

[4] In 1906, DeJarnette worked with Aubrey Strode and Albert Priddy to establish the Virginia State Colony for Epileptics and Feebleminded in Lynchburg.

[6] "To this class of the unfit belong the insane, the epileptic, the alcoholic, hereditary criminal, the syphilitic, the imbecile and the idiot, and none of these should reproduce," DeJarnette wrote.

Trinkle advocated the compulsory sterilization law as a cost-saving strategy for public institutions that had experienced growth in the incarceration of what he referred to as feeble-minded and defective populations.

Trinkle added that legalizing sterilization for the insane, epileptic, and feeble-minded persons would allow these patients to leave the institutions and not propagate their own kind.

He remained in charge of the semi-private DeJarnette Sanatorium until 1947 and continued to advocate eugenics after the Nazi Holocaust was exposed at the end of World War II.

It was converted to a children's mental hospital in 1975, at which time it ceased to be a private enterprise, and the state of Virginia took over operation of the facility.