Davy Crockett at the Alamo

Staying up last night with the baby I managed to catch a Discovery Channel special on the Alamo.
I know it is an old issue and all, but it still irritates me when I have to listen to all the debate about the Jose Enrique de la Pena diary and whether it proves that Davy Crockett was captured and executed by Santa Anna.

The first thing that struck me about the show was that de la Pena apparently had two diaries. The first was written in his own hand and was a journal that he kept during his travels with the Mexican Army. There is little doubt about the authenticity of this first document which is certainly a valuable contribution to our historical knowledge. But nowhere in this first document is there any mention of Davy Crockett being captured at the Alamo. He apparently didn't find that little tidbit of information important enough to mention in his daily journal at the time. Instead, it shows up in the second set of documents which were allegedly transcribed by de la Pena many years later while he was sick and dying in prison. This second set of documents which were written by as many as five separate people contain the controversial account of Crockett's execution.
The Discovery Channel show spends an inordinante amount of time trying to determine whether the second set of documents could have been forged. Their conclusion is that there is no evidence to support claims of forgery.

This is all fine. But why does it therefore follow that the story told in the document is true and accurate? The Discovery Channel show just assumes as much. To accept de la Pena's account we have to disregard the eyewitness accounts of two other people present at the aftermath of the battle - Susanna Dickinson and Travis' slave, both of whom identified Crockett's remains surrounded by dead Mexican soldiers.

Let's assume that the second set of documents are not forgeries and also that de la Pena was telling the truth as he remembered it.
Could someone please tell me how Mr. de la Pena would have even known what Davy Crockett looked like? At least Mrs. Dickinson and Travis' slave had the opportunity to meet and see Crockett in person. De la Pena at best might have at one time seen a drawing of Crockett though that is never addressed in any of the historical accounts. Was this person wearing the famed coonskin cap? That was common headgear for many of the Tennessee volunteers at the Alamo.
Did this person identify themselves as Crockett? How do we know it wasn't someone else pretending to be Crockett in the hope that it would save his life.
All in all I find the de la Pena account of Crockett's death to be wholly unconvincing and I'm constantly amazed when I hear historical reports about his accounts that fail to raise these obvious questions.