Chelsea Lopez is the main antagonist from "Hell Night", episode 3.06 of CSI: Miami.
Chelsea Lopez is the daughter of the famed baseball player Donny Lopez and his wife Miranda (who was murdered some time before the episode's events). Donny was accused of killing his wife and was held on trial, but in a shocking occurrence, Donny was found dead in his home, where the jury from the trial was visiting to inspect the crime scene.
Chelsea was interviewed by Calleigh Duquesne regarding her father's murder, and was quickly cleared when notebook paper left at the scene (which had the word "Guilty" written on it) did not match the paper from Chelsea's book. Donny's killer was revealed as Jim Wilson, one of the jurors, but during the interrogation, Calleigh noticed something in a photo of Miranda that proved that Donny did not kill his wife. The shallow stab wounds led to the conclusion that Miranda's killer was female, and after Donny's girlfriend, Kelly, was interviewed and cleared, evidence revealed that Chelsea had killed her own mother.
On the night in question, Chelsea spotted Donny in the car with Kelly, and she later told Miranda, who did not believe her daughter's claims. An angry Chelsea shoved Miranda and later took possession of one of the knives, after which Miranda attempted to calm her daughter down. Miranda extended her hand and grabbed the blade, only for Chelsea to pull back the knife, cutting Miranda's hand. Shortly afterwards, the evil Chelsea stabbed her mother to death, and after the murder, Donny - seeing his wife dead and the knife next to the body - cleaned up the scene. Though it was never revealed if Donny was aware that his daughter was the killer, but his actions led to him being accused of the murder.
During her interrogation with Calleigh, Chelsea attempted to portray Miranda as being violent and combative during the night of the murder, claiming that she was afraid of what her mother would do to her. However, Calleigh showed Chelsea the photo of Miranda's right hand; evidence that Miranda was attempting to reach out to Chelsea and showed trust in her, only for Chelsea to betray that trust and kill her. The villainess broke down and stated that she wanted her parents to be happy and be together like they were in public, while also saying that she missed her mother. Afterwards, Chelsea was then arrested for her crimes (off-screen).