New information points to four Ku Klux Klan members as almost certainly responsible for the unsolved murders of two civil rights activists who died when their home exploded in 1951, Florida officials say.

Attorney General Charlie Crist announced Friday that investigators had begun excavating the site of Harry and Harriette Moore's home, which was blown up on Christmas night in 1951.

Detectives were searching for detonators and other evidence that could prove what type of explosive was used.

The four suspects, all members of the Florida Klan at one time, had experience with dynamite, said Frank Beisler, an investigator with Crist's office.

Beisler said the major break in the recently reopened investigation came about a month ago when he interviewed a man to whom one of the bombers had confessed.