The Talented Mr. Ripley by Patricia Highsmith
Tom Ripley had a rough childhood in Boston. Things did not get much better when he moved to New York City. There he got by as a con artist. He would impersonate the IRS to get extort money from people. He also remembered details from conversations with people and would use that to fake friendship or mutual connections.
Mr. Greenleaf was a wealthy man who wanted help getting his son back from a bohemian lifestyle in Italy. He believed Tom was a friend of his son Dickie and hired him to go help bring him back. Tom went to Italy and ingratiated himself with Dickie. Things start to go sour after Dickie catches Tom wearing his clothes. One day while alone in a boat away from land, Tom decides to kill Dickie and carries it out. He then lives alone in Italy, pretending to be Dickie and forging his signature to cash trust fund checks. After a while, a friend of Dickie's tracks him down. Tom kills him, too. However, this body is quickly found and investigated. He also learns that the boat was found and the authorities suspect Dickie of murdering Tom. This leads Tom to go back to being himself.
Tom concocts a story of Dickie being mentally unstable. Tom even forges a suicide note and will. Tom survives a few clothes encounters with Dickie's father and on-and-off girlfiend Marge. He also evades the authorities, with them believing that Dickie likely murdered his friend and then committed suicide. Tom now could live a life of wealth.
The book is a story of a mind that escalates to worse and worse things as he continues to get away with it. Punishment came early in life and is totally disconnected from his behavior.