SEATTLE (AP) _ It's been a month since poisoned medicine capsules killed two people in suburban Auburn, and investigators admit they're finding few solid clues to the mystery of who substituted cyanide for a painkiller.

''We're finding out what's been found elsewhere - there are no easy answers in dealing with these kind of senseless, apparently unmotivated acts,'' said Chuck Kleeberg, chief of environmental services for the Seattle-King County Health Department.

No one has claimed responsibility for the deaths of Bruce Nickell on June 5 and Sue Snow on June 11; no arrests have been made.

''It's difficult to track down with no one appearing to take claim for it and without us coming up with a motive yet,'' said Auburn police officer Bob Karnofski.

Police don't know if the crimes were deliberate or random, or where the tampering was done, Karnofski said.

''It's going very slowly because of all the possibilities we have to check out. The investigation is progressing in the sense we're able to eliminate certain possibilities,'' he said, declining to elaborate.

In all, five tainted bottles were found in southern King County, four of Extra-Strength Excedrin and one of Anacin-3.

The Anacin bottle was marked with an Associated Grocers price tag, but found in a Pay 'N Save store in Auburn. Gil Harding, an Associated Grocers spokesman, said his company does not distribute products to Pay 'N Save.

FBI spokesman Joe Smith said his agency is protecting its investigation by declining to release information. Smith did say, however, that agents believe it's an isolated, local case.

But health officials say they have to assume a larger area is at risk.

''We're not privy to what FBI investigators are finding out,'' Kleeberg said.

''It's become pretty apparent that they don't have much to go on once they eliminated the families as suspects,'' said Paul Webking, Ms. Snow's husband.

Webking said he and his family were questioned repeatedly, and he was the subject of a wide background check. Once he passed a lie detector test, the questioning stopped, he said.

''I have little or no interest in the investigation now. ... To have frustration in this area would be not to deal with the fact she's dead. It's not like whoever did this directed this action at Sue,'' Webking said.

Dr. Bud Nicola, director of the Seattle-King County Health Department, said he asked capsule manufacturers what they could do to improve tamper-resista nt packaging.

The health department also considered setting up places where consumers could bring capsules for cyanide screening, but found such an effort would be impossible to arrange, Nicola said.

Meanwhile, state officials are trying to decide what to do with a 90-day statewide ban that began June 27 on the sale of non-prescription medication in two-part, nonfused capsules. King County also banned two-piece capsules of vitamins and food supplements.

The state ban will be discussed at a meeting on Aug. 14 in Seattle, said Don Williams, director of the state Pharmacy Board.

Bristol-Myers, the maker of Excedrin, withdrew all non-prescription capsules from the market June 20.

Asked if the company would improve its packaging, company spokesman Jerry Parrott said: ''We're going to continue to track technology in this area. It is possible if technology improves to the level where we're comfortable ... we could make adjustments in our marketing plans accordingly.''