Hickock and Perry Smith fled to Florida in a stolen car after the Clutter murders in Kansas. They checked out of a Miami Beach motel on Dec. 19, the day the Walker family was killed, and at some point that day bought items at a Sarasota department store.
Witnesses have said they spoke with Smith and Hickock in Tallahassee on Dec. 21.
McGath said the Walkers were considering buying a 1956 Chevy Bel Air, the kind of car Smith and Hickock were driving through Florida. McGath thinks the Walkers met with the men because of the car.
Smith and Hickock were later arrested in Las Vegas. A polygraph test cleared them of the Walker murders, but a polygraph expert said in 1987 that such tests were worthless in the early 1960s.
The reason it is now feasible to do these tests is the technology has advanced to the point where they will be able to get the DNA out of those old bones. In the past, they might have tried without success, and destroyed all the available test material in the process.
I thought Truman Capote covered Hickock and Smith's entire lives in that book, so I'll have to read it again to see what he says about them going to Florida.
As close as Capote claims he became with those guys, he surely would have gotten a hint that they had committed additional murders because they weren't bright enough to carry it to their graves. Maybe they told him, and he chose to ignore it because it didn't jibe with his story, but there again, I wonder if Truman Capote would have been able to keep that kind of secret.

The Walker family.