@hawkeye10,
You make an excellent point however no one knows what a jury discussed as they deliberated.
The Grand Jury is secret as well. Just a quick glance at the last 14 Death penalty cases here no fiber or hair issues was needed for the convictions,
You could find the true bill used for the indictment and if hair and fiber evidence was provided by the FBI you could appeal on those grounds.
Just how is that going to work for all these cases. Surely you can see that it is impossible to ever know if an executed man was convicted based on faulty evidence provided by the FBI.
Ted Bundy was convicted and executed for the rape and murder of 12 year old Kimberly Leech. Fibers from the van and the crime scene were matched by the FBI however there was a mountain of other evidence to convict him.