A death row inmate who became a murderer when he was 16 and is believed to have claimed three victims is set to be executed in Florida nearly 40 years after his most recent crime.

Ronald Heath, 64, is scheduled to be executed by lethal injection on Tuesday, Feb. 10, for the murder of a 30-year-old traveling salesman named Michael Sheridan in 1989. Prosecutors say Heath also killed a 26-year-old man during a robbery just days after Sheridan's murder, and was convicted of killing an 18-year-old in 1977.

"In matters of murder and robbery, Ronald shows no weaknesses," Florida Judge Robert Cates said when affirming a jury's 10-2 decision to sentence Heath to death.

Heath's execution will be the second in the U.S. this year and the first in Florida, which put far more inmates to death last year than any other state.

Here's what to know about Heath's execution, the three killings connected to him, and how the victim family members feel about the execution finally happening nearly 40 decades after his conviction.