Correct, that is actually the origin of the word.
SINISTER:
(Archaic) on, to, or toward the left-hand side; left
(Heraldry) on the left side of a shield (the right as seen by the viewer)
threatening harm, evil, or misfortune; ominous; portentous: sinister storm clouds
wicked, evil, or dishonest, esp. in some dark, mysterious way: a sinister plot
most unfavorable or unfortunate; disastrous: met a sinister fate
http://www.yourdictionary.com/sinister#8e9qhgsmPDxhdoP3.99