By Kevin Murphy

KANSAS CITY, KANSAS (Reuters) - DNA tests failed to prove a suspected link between the 1959 murders of a Kansas family portrayed in the book "In Cold Blood" and a quadruple homicide in Florida later the same year, authorities said on Tuesday.

However, the inconclusive testing was based on poor DNA samples that had undergone years of storage and handling.

Richard Hickock and Perry Smith were executed in 1965 for the murders of the Clutter family in Kansas and remain "the most viable suspects" in the Florida murders, they said.

Investigators exhumed the bodies of Hickock and Smith in December to obtain DNA samples to compare against evidence in the Florida murders.

Investigators never solved the murders of Cliff and Christine Walker and their two children in Osprey, Florida. The Florida murders took place about a month after the November 15, 1959 shotgun killings of Herbert and Bonnie Clutter and two of their children near Holcomb, Kansas.

The murders of the Clutters were reported in detail in Truman Capote's best-selling book "In Cold Blood," which later became a movie.

Hickock and Smith fled to Florida after the Clutter murders and were in the Osprey area at the time of the Walker killings, Sarasota County detectives have said.

Both sets of slayings involved a couple and their two children.

"Based on the totality of the evidence, investigators still regard Smith and Hancock as the most viable suspects in the Walker murders. However, DNA testing seems unlikely to provide conclusive evidence one way or the other," the statement said.

Hickock and Perry passed lie detector tests when questioned about the Walker murders. After their capture in Las Vegas. Smith had a knife identical to one stolen from Cliff Walker, case evidence showed.

(Editing by Ellen Wulfhorst and Lisa Shumaker)

[Scientist studies DNA in lab via Shutterstock]