The witness has a verified faulty memory. That was diagnosed when she was a child, and there has been no improvement. The brain injury was permanent. She recalled seeing a man that was 5 feet tall, she agreed with investigators that the 5 foot tall man looked like Jason. She added other details to help bolster her story, but nothing she said could be verified ... most likely because none of it was a true memory.
Eight years later, everyone's memory fades. If the ability to lay down memory was faulty to begin with, then eight years later tells me that there's very little, if anything, of the memory left. That's my opinion, of course. I suspect that with a little plodding, the witness will be encouraged to remember when the police visited her at the gas station and when she last testified in court, but that's not a memory of Jason.
Although it would be cruel, if I were the defense, I would absolutely destroy the witness and lay it at the feet of the prosecution for attempting to present someone like that as a reliable witness ... for attempting to put someone in prison for life on the basis of a mixed up statement from an unreliable witness.