Standreid said: "I don't know what the geographic profile was but to me the hub looks to be somewhere in the vicinity of Elmhurst. If the killer knew anything about geographic profiling, however, "he" may have skewed the pattern to leave a false impression."
Geographical profiling was very much a part of the investigation. This case, where the Perp is presumed to have gone on only one "mission" would be different than a serial killer or a rapist. There was an assumption that the Perp started at a particular point and made a route to each of the "plant sites" and then returned to the starting point; probably his residence.
We know that 8 bottles were planted in seven different stores. Information on one of the stores has been withheld and it is likely that other tainted bottles were planted at other stores but they were destroyed by the distributer soon after the tylenol angle was discovered. Per Bartz, large retailers like Jewel Osco sold about tylenol two bottles of ES tylenol a day and most OTC pain killers are used soon after purchase.
From this, one could conclude that the first death would occur within a few hours of a plant. Mary Mcfarland died Tues evening shortly after purchasing a bottle. For this reason it was concluded that the "run" was made Tuesday afternoon.
A logical route would be to start with the Walgreens in Chicago Northside and then to Arlington Heights then south to Lombard and east to Winfield; or the reverse. Since the basic profile of the perp was a lower income, single, white male, and there is more appropriate housing in the Northside than out in the affluent low density suburbs around Winfield, it was speculated that the perp lived in a lower income neighborhood near the Walgreen's. Seems reasonable but by no means certain. (for what its worth, Lewis live in this general area) Why he chose a comparably small store in an obscure town like Winfield is a good question.
My own WAG (wild



guess) is that the perp wanted to cause "wide spread panic", not just a local panic. He may have figured that suburban areas were easier to move "mall to mall" but to get real publicity, one of the deaths had to occur in Chicago proper. Again, why Winfield?