How are the characters reminded of guilt for the crimes they have committed?

The only character who is reminded of his guilt concerning the fate of Jay Gatsby is Tom Buchanan. Following Gatsby's death, Nick Carraway recalls running into Tom Buchanan one October afternoon on Fifth Avenue. Nick initially refuses to shake Tom's hand and proceeds to ask Tom what he told George Wilson. Nick reminds Tom of his involvement in Gatsby's death and Tom admits that he informed George that Gatsby was responsible for Myrtle's death. Tom experiences guilt and reluctantly tells Nick,

What if I did tell him? That fellow had it coming to him. He threw dust into your eyes just like he did in Daisy’s but he was a tough one. He ran over Myrtle like you’d run over a dog and never even stopped his car. (Fitzgerald, 191)

After admitting to telling George Wilson that Jay Gatsby killed his wife, Tom demonstrates his selfish personality by lamenting how Myrtle's death negatively impacted his life. Nick then refers to Tom and Daisy as "careless people" who destroyed things and simply retreated back into their wealth while other people cleaned up their mess.
Nick does not run into Daisy after Gatsby's death, and the only character reminded of their guilt regarding Gatsby’s fate is Tom Buchanan. From their conversation, it is evident that Tom feels somewhat guilty after Nick confronts him but insists that Gatsby had it coming. Overall, Tom and Daisy Buchanan are portrayed as completely selfish, callous individuals, who hide behind their money and refuse to accept responsibility for their actions.

The only character I can think of who is reminded of his guilt is Tom Buchanan. This occurs when Nick runs into Tom on Fifth Avenue in New York City in October. Tom is looking into the window of the jewelry store when he sees Nick's reflection and turns to greet him.
Nick doesn't want to shake his hand, which reminds Tom of the events that occurred around the time of Myrtle and Gatsby's death. He feels guilty and becomes defensive. Nick asks him what he said to George Wilson before Wilson shot Gatsby. Tom tells Nick that he told George the car that ran over Myrtle was Gatsby's, suggesting that Gatsby was responsible for Myrtle's death. Then, Tom's guilt rising, he bursts out, "what if I did tell him? That fellow had it coming to him". Therefore, it is Nick who reminds Tom of his guilt.