Harold, a CPA, has a new client who recently moved to town. Harold prepares the client's current-year tax return, which shows a net § 1231 gain. Harold calls the client to request copies of the returns for the preceding five years to determine if there are any § 1231 lookback losses. The client says that the returns are "still buried in the moving mess somewhere" and cannot be found. The client also says that he does not remember any § 1231 net losses on the prior year returns. What should Harold do? Justify your answer.