That might enable investigators to trap spies who lie about their finances.
This kind of physical evidence enabled investigators to quickly solve the Oklahoma City bombing in 1995 and the first World Trade Center attack in 1993.
Eventually, this could enable investigators, for example, to quickly sort out all mail from Trenton in search of other contaminated letters.
The huge volume of material gathered enabled investigators, much to the annoyance of the military, to extend the mandate for nearly two years.
Retrieving the second one is important because in some past jetliner accidents, information from the two recorders, together, has provided a level of detail that has enabled investigators to pinpoint causes.
When the card, which operates like a debit card, is passed through a scanner, the time, date, location and amount of the transaction are recorded, enabling investigators to search for irregularities, he said.
More likely, they will remain research tools, enabling investigators to develop new laser procedures, which will then be carried out by less costly and less sophisticated medical lasers.
Ms. Tripp apparently did not date the tapes, but they include enough references to extraneous events that may enable investigators to provide some dates, according to the lawyers.
Officials in Sacramento went ahead with the case recently after new technology enabled investigators to tie the four defendants to evidence at the scene.
A computer in the tower will record every push of a button and flick of a light, enabling investigators to reconstruct the sequence of events in case of a mishap.