One of Florida's prisoners scheduled to die in July, a man convicted of killing his ex-girlfriend's parents in 1986, is 80 years old and would be only the second known octogenarian to be executed in the U.S.

Florida is in the process of executing three of its oldest death row inmates back to back — each one older than the last.

The series of executions, due to be carried out by the end of this month, highlights the nation’s aging death-row population.