The cab driver's alibi was that he had dropped off a passenger at the station and the passenger left the bag in the trunk. This was circa 2011. New York City post the 9/11 attacks has an extensive video monitoring system, especially around high value targets such as train stations. The investigators then as a part of the investigation would have been able to see the taxi and if someone else got out. If someone had gotten out, then this would have deflated the entire premise of the story as the driver would not have been arrested and detained for 6 years.