(CNN) -- Human remains found buried under recently-added concrete at a home in Plant City, Florida, are likely those of missing lottery millionaire Abraham Shakespeare, police said Thursday.

Deputies made the discovery after a tip came in, suggesting investigators would find a body near a home in Plant City, according to CNN affiliate WFTV.

Hillsborough County Sheriff David Gee said the body was slowly being uncovered. They are awaiting positive identification.

However, Gee said their investigation and information specifically led them to the area after they began to believe he might be dead because of "sinister means and motives."

"Our indications were it would be there," Gee said during a news conference Thursday night.

Police on Wednesday had scanned the newly finished concrete slabs near the home on Wednesday and removed it. On Thursday, Gee said they discovered the remains buried five feet below the surface, and it appeared the remains had been there for awhile.

Shakespeare, a 43-year-old truck driver, won a $31 million Florida lottery prize in 2006. A year later, he won a court challenge from a fellow trucker who accused Shakespeare of snatching the winning ticket out of his wallet while the two were delivering meat to Miami restaurants.

Shakespeare's family reported him missing on November 9, telling the Polk County sheriff's office they hadn't seen him since April.

Polk County Sheriff Grady Judd said when their investigation began, they had hoped to find Shakespeare alive "and he truly had just wanted to hide from those who were asking him for money."

"As our investigation continued, the information we developed led us to believe he may very well have ended up with an untimely death," Judd said.

Both Judd and Gee said they would not comment on whether anything else was found inside the manmade grave, or whether a previous person of interest was connected to the area. The home, according to WFTV, belongs to the boyfriend of a person of interest in the disappearance of Shakespeare.

While they await identification of the remains, police said they would begin to shift their focus to a murder investigation.

"It's painfully obvious he didn't get there by himself," Judd said.

Gee said police from Polk and Hillsborough Counties were already working with prosecutors on the case and hope to bring to justice the person responsible for what they believe is clearly cold-blooded murder.

"Somebody put that body in that hole," Gee said. "This isn't by any means just where we find someone on the side of the road. Somebody has obviously put him there."