Women vs. desire of the ring

[Elfstone]

And yet did it turn Smeagol into a murderer in one day.

Valid point. But I would contend that of all the characters that knowingly came into contact with the Ring after Isildur, only Smeagol was ripe for instant corruption. If we look at Bilbo, Thorin and Co., Gandalf, Frodo, Sam, Merry, Pippin, Fatty, Bombadil, Aragorn, Elrond and Co, the rest of the Fellowship, Galadriel and Celeborn, every one of them are "good" people. Some more resistant (the Halflings), some less so (Boromir), but not a one whose intentions towards others is called into question.

Not so with Smeagol. He is an unsavory character. His own people ran him off. But Bilbo and Frodo both possessed the Ring for many, many years in the Shire without it seducing them to evil. It strikes me that killing Deagol in order to rob him of the Ring isn't a far leap for Smeagol, the way it would have been for Frodo to kill Bilbo and take it.