In the Season Five finale of Dexter, titled "The Big One," there appears to be a fatal plot flaw.
Recall that Dexter used a car which he had stolen near the crime scene where he killed Stan Liddy to rescue Lumen. Upon arriving at the camp where Jordan had kidnapped Lumen, Dexter has a car accident in which the stolen car actually spins and rolls violently out of control. That car isn't going anywhere. Certainly, Dexter and Lumen could not have possibly taken care of the stolen car after killing Jordan.
Next, Debra arrives at the crime scene where Dexter and Lumen have just killed Jordan. She permits Dexter and Lumen to flee but states that she will "call it in."
Investigating officers should have seen the stolen vehicle, matched it to a reported missing/stolen vehicle (stolen near the Liddy crime scene that Dexter had recently inexplicably fled), and continued to pursue that lead.
Quinn would have certainly become more curious about anything that would potentially exonerate him from Liddy's murder. And the fraudulent results Dexter reported regarding the blood found on Quinn's shoe doesn't seem adequate to excuse Quinn as a suspect.
So, why was this evidence never investigated further?