Deputies said a family member reported Layton Underwood, 75, and Donna Underwood, 69, missing on Sunday. The family member said they hadn't heard from the couple since Christmas.
During the search for the couple, deputies said they found what could be human remains on their property.
Detectives said they are also looking for the couple's vehicle and a relative that may be driving it. Deputies believe Allyn Shane Gilbert, 53, may be driving the Underwood's 2014 White Volkswagen Passat S. The car has Florida tag GXRD85.
Deputies described Gilbert as a missing endangered subject because of what they called "concerning statements he's recently made."
Layton and Donna Underwood are also considered missing and endangered, deputies said.
When Channel 9 asked investigators why are they saying possible remains, they said it's because of the condition they were found in, experts will have to make sure the remains are human.