During a criminal investigation, the Government secured a series of court orders authorizing electronic surveillance of respondents, as mandated by Title III of the Omnibus Crime Control and Safe Streets Act of 1968, 18 U.S.C. 2510 et seq. Section 2518(8)(a) requires, in pertinent part, that: (1) recording "shall be done in such way as will protect the recording from editing or other alterations"; (2) "[i]mmediately upon the expiration of the period of the order, or extensions thereof," the recordings are to be made available to the judge who issued the order and sealed under his directions; and (3) "[t]he presence of the seal . . . or a satisfactory explanation" for its absence is a prerequisite for the use or disclosure of the evidence obtained from the recordings. Among the orders obtained, was an April 27, 1984, order for the surveillance of respondent Ojeda Rios Levittown, Puerto Rico, residence and some nearby public telephones, which was extended until July 23, when he moved to another community. On July 27, the Government obtained a n