Underwater Alien Bases: The team investigates what appear to be underwater landing strips and other strange evidence in the wake of UFO sightings in Florida. (S3, ep 5)

The Real Roswell: The story of a UFO crashing in Roswell is the most famous case in UFO history. Now, a theory has emerged that there was more than one crash site. (S2, ep 5)

Abductions: This episode chronicles several close encounters with alien abductees who have been held captive, probed, examined and had objects implanted in their bodies. (S1, ep 5)

Nazi UFOs: Upon learning about a connection between the UFO phenomenon and the Third Reich, the team travel to Germany and Poland to investigate. (S3, ep 4)

First Contact: Experts investigate a reported crash of an alien craft in Texas in 1897, debris of which was allegedly thrown down a well and an alien body buried locally. (S2, ep 4)

The Bathtub Killer: A look at the tense search for Bathtub Killer Dale Devon Scheanette, who was executed in 2009 for murdering two women in Arlington, Texas. (S3, ep 13)

Cold Fusion: Cops go on the hunt for a killer when the leading advocate for the controversial science of cold fusion is beaten to death. (S8, ep 12)

Little Girl Gone: The 1988 case of a missing nine-year-old girl went cold until an encounter at a bus stop breathed new life into the investigation and revealed the truth. (S7, ep 12)

Nightclub Nightmare: When a robbery at a popular Texas nightclub leaves one dead and two critically wounded, investigators are in a race against time to catch the killer. (S6, ep 12)

When Evil Strikes: Detectives race to solve the murder of North Carolina factory worker Jonathan Blackwell, whose body was found two years after he disappeared in 2004. (S5, ep 12)