Mr. Morden became an agent for the Shadows. When he arrives at Babylon-5, he is questioned by Captain John Sheridan. Morden claims he has no memory of the destruction of the Icarus and that for several months after he was found, he didn't even remember his own name. He also says after he was found, he was taken to a medical station after the Icarus accident. Surely the medical crew would do a DNA search on him. Wouldn't Earth government know who Mr. Morden is from his DNA? If it is that easy to identify somebody, Mr. Morden never should have claimed the medical staff could not identify him. And there would be a document trail of his time at the medical station.
In this video clip, Sheridan easily exposes Morden's lies with only a few questions.
Why would Mr. Morden make claims about his survival of the Icarus which are so easily disprovable? It would seem better for him and his Shadow handlers to give him a convincing alibi. If their spokesman is going to talk to high government officials, then surely the Shadows would want a credible person doing the talking.