Two twin sisters are found dead in opposite sides of Las Vegas. Amanda Sinclair is shot to death outside a dry cleaner. David Phillips and Catherine are in the crime scene and Catherine identifies the woman by her Lexus car and does not find her purse. Nick verifies the nearby dumpsters and finds her purse and the stocking used by the killer. Nick finds also a short letter from "Dora". Grissom and Warrick investigate the death of the Chief-Editor of a newspaper Jill Case, who apparently committed suicide hanging herself from the second floor. Warrick sees pictures of Jill with Nelson Mandela and Bill Clinton and notes that she has no children. Soon Dr. Robbins realizes that Amanda and Jill are identical twins. Catherine believes the cases are related, but Grissom is not sure. They begin to interview Amanda's husband Gary and Dora Pomerantz, whose fingerprints are on the envelope in the purse retrieved by Nick. Dora tells that she is the biological mother of the twins and she put them up to adoption after the death of their father in Vietnam. They proceed their investigation to find the motive and the killer of the women.
"Happenstance" is a mysterious and engaging episode of "CSI", with the death of twin sisters that do not know each other. The investigation of the team is top-notch and the reason why the killer murdered both sisters is an amazing coincidence. My vote is seven.
Title (Brazil): "Happenstance"