Police said the murders of 68-year-old A.C.Worthy and 55-year-old Carolyn Worthy in their Tuscaloosa driveway are linked to the slaying of a wealthy Florida panhandle couple.
Both crimes took place in 1989.
A wealthy Graceville, Florida couple, Robert and Kathryn McRae were also shot execution style in a similar home invasion robbery.
Two ski masks were found at the McRae's home in Northwest Florida. That gave authorities the clue that at least two people committed the crimes.
Police won't say what piece of physical evidence linked the two killings, but they say it was unusual.
At least $110,000 in reward money is available for anyone with information about the four killings.