Absolutely correct. And in this specific case, it looks as if eyewitness testimony which is 40 years old would almost have to be used to support any charges and evidence emerging from the current investigation.
To date, all the search warrants issued have been on the basis of statements made by Lloyd Welch (and possibly others) which relate directly to events of 1975. Any evidence found today as a result of those searches will need to be validated in court by documentation and possibly by first hand testimony.
Any testimony proposed or given can be challenged in court and a judge would have to rule on its admissability. Elapsed time is certainly a factor, but not necessarily the only one. It is one thing to remember how something happened 40 years ago, as you saw it, but quite another thing to render a positive identification of a suspect 40 years later of someone you did not know at the time.
There could be a number of factors which might tend to support or oppose allowing such testimony, and they might be introduced by either the prosecution or the defense depending on the situation at a trial - and on who is on trial.
If, for example, Lloyd Welch were to be tried for abduction of the girls, his attorney would probably oppose any attempt to identify him as LHM and to place him at the scene. But, if Lloyd were to appear as an eyewitness, claiming to have been at Wheaton Plaza that day, he might want to claim that he was indeed LHM, as described by the girl witness of 1975.
