Ill try to take a shot at the only way I am familiar with how she could have sent the texts to her phone and make it appear Travis sent it to her.
This is simplest way I can see JA doing it. And this may explain why Juan didnt want to try to prove it because remember we heard just yesterday that the computer came up as Deanna's computer which we know is Travis computer he got from Deanna.
Here goes....
Since we know JA had access to Travis email account. Lets just say GMAIL for instance.
Step #1 - JA is sitting at home on her computer and she logs into Travis GMAIL account. She then formats the message and then uses the simple instructions in this link below to send it to HER phone directly from his GMAIL account.
Her phone would receive the message as a text message from him.
And the important thing to realize is when LE looked at Travis computer in his SENT box of his GMAIL account on his computer, that same message would show as being sent from his computer because it is still in the GMAIL SERVER "sent" area of his email account.
http://www.wikihow.com/Text-from-a-Computer-to-a-Cell-Phone
Another Approach: #2
She could do the same thing, but instead of sending it as a text message to her phone, she could send it from his GMAIL as a regular email message from his email account over to her email address.
She would then login to her GMAIL account (instead of his), and receive the message and then either leave it there to make it look like she got an email from him (OR) forward it to her phone using the same method from the link.
