Both Uses

sinister
in
Farewell to Manzanar
(Edited)

The confiscators were often deputies sworn in hastily during the turbulent days right after Pearl Harbor, and these men seemed to be acting out the general panic, seeing sinister possibilities in the most ordinary household items: flashlights, kitchen knives, cameras, lanterns, toy swords.
Chpt 1.1

sinister = evil, harmful, or frightening
In later years he would tour the country with Mr. Moto, the Japanese tag-team wrestler, as his sinister assistant Suki—karate chops through the ropes from outside the ring, a chunky leg reaching from under his kimono to trip up Mr. Moto's foe.
Chpt 1.3 *

Definitions:

(1) (sinister)
evil or harmful; or making an evil or frightening impression
(2) (meaning too rare to warrant focus)
Much more rarely and only in very old usage, sinister can refer to the left side of something.