A common FDA inspection finding and a typical citation follows:- "You failed to retain records required to be maintained by the clinical investigator under 21 CFR part 312 for a period of 2 years following the date a marketing application is approved for the drug for the indication for which it is being investigated; or, if no application is to be filed or if the application is not approved for such indication, until 2 years after the investigation is discontinued and FDA is notified [21 CFR 312.62(c)]. ... Your failure to retain records of this clinical study makes it impossible for FDA to verify the integrity of the data and to verify that there was adequate protection of the rights, welfare, and safety of the subjects who participated in the study". CFR = Code of Federal Regulations.
The FDA inspectors often request that the PI be available for interview and this is often arranged by a visit by the PI or, in agreement with the FDA inspectors, the use of a teleconference. It would be helpful if other members of staff who worked on the trial were also available.

The UK's MHRA GCP Guide (2012) section 10.7.1 has some good advice:- "The ultimate responsibility for the documents to be retained by the investigator or institution resides with the investigator or institution. If the investigator becomes unable to be responsible for their essential documents (for example, relocation, retirement) the sponsor should be notified in writing of this change and informed as to whom the responsibility has been transferred"..... "Investigators can retire, hospitals can close and vendors (some of which are also investigator sites, such as, commercial phase 1 units) can go out of business or be acquired by other organisations. The sponsor should ensure that agreements cover such eventualities to ensure that the documentation remains available for inspection for the specified retention time".