One way to judge the credibility of Jasons testimony and alibi is to see if there are any lies. One that comes to mind is that Jason said he went to his car to retrieve his charger and reviewed his sales software until 11:53, but computer forensics shows that he did not use his sales software that night.
Another one is the sheer unlikelihood that he went outside to smoke a cigar and look at the paper in freezing and gusty weather. It would be different if he were a habitual smoker and had to get his nicotine, no matter the weather. But he wasnt. No one had ever even seen him smoke a cigar and all reported that he was a vocal anti smoker. It seems so unlikely that Jason would have chosen that one night to smoke a cigar and in such unpleasant weather conditions.
Another likely falsehood is his story about the Coach purses and ebay searches. Computer analysis shows the searches were completed at 7:23 and he was getting gas at 7:30. Those printouts were done immediately before he left the house, so it is so improbable that he waited for them to print out and then turned them upside down and left them instead of putting them in his bag as he was leaving. Also, he printed out other materials around the same time and managed to bring those with him, but accidentally left behind only the ebay printouts? That is so improbable that it cannot reasonably be true.
Do any of those lies prove hes a murderer? Of course not, but if hes lying about things in his alibi, you cannot take it as true.