The paid informant for the Drug Enforcement Administration who had difficulty recalling some specific details in testimony last week was recalled to the stand yesterday by lawyers representing five defendants accused of involvement in a worldwide drug ring.

John R. Snow of Naperville, Ill., returned to U.S. District Court in Alexandria after defense lawyers learned the government had withheld vouchers documenting the dates and sums of money paid Snow for information linking five defendants in a lucrative drug conspiracy.

The date when Snow, a truckdriver, went to work for the DEA is considered critical by the defense. On Friday, presiding Judge Albert V. Bryan Jr. noting that U.S. prosecutors had delayed revealing their use of a paid informant ruled that any information given the DEA by Snow after he became an informant would be excluded from evidence. As a result, defense lawyers have been endeavoring to establish that Snow was actually an unpaid DEA informant as early as May 1977.

On Friday, under cross-examination, Snow said he first became an informant last February. Then he altered that date to "after Christmas" 1977, then "around Thanksgiving" 1977 and, ultimately, "in May 1977."

Yesterday Snow said he could not recall having given the government information prosecutors said he had supplied, denied his informant's identification number was the one the government said it was and said repeatedly he was unable to recall filling out a DEA form the government alleged he had filled out.

The defense rested its case yesterday and closing arguments are scheduled today.