How does Stevenson create a sense of evil in Dr. Jekyll and Mr Hyde?

The author creates tension and evil with the creation of Edward Hyde, the product of Dr. Jekyll's experiment.

"The Strange Case of Dr. Jekyll and Mr. Hyde is based on the story of Edinburgh's infamous Deacon Brodie, who was discovered to have been living a double life, coupled with a dream Stevenson had one night, what he called "a fine bogey tale," about a man who drinks a potion made from a white powder and subsequently transforms into a devilish creature."

Suspense is also felt in not knowing what Mr. Hyde, who is a totally immoral individual, will do once he emerges and takes control of Dr. Jekyll.  Hyde is unpredictable and violent.

Edward Hyde reflects the ugly side of the human spirit.  He embodies evil with such ease, it is very frightening to imagine a killer more manipulative, sadistic and indifferent that Hyde. He represents the dark passions that exist in all of us, except in Hyde's case they are in total control of both mind and body.  What is really eerie, is that Jekyll finds himself enjoying his alter ego's escapades.

"Part of him as Hyde "felt younger, lighter, happier in body" and more free than Jekyll ever had, while at the same time he recognized this new creature as "pure evil." Jekyll continued taking the potion until one night he found himself transforming without the drug and noted that Hyde was getting stronger."