A death row inmate who became Florida’s oldest executed prisoner was branded a “lifelong brutal and sadistic man” by his murder victim’s heartbroken sister.

Dennis Sochor, 74, died Tuesday evening following a three-drug injection at Florida State Prison near Starke.

He was convicted of killing Patricia Gifford on January 1, 1982, after meeting the 18-year-old at a New Year’s Eve party at a bar in Fort Lauderdale.

After witnessing the execution, Patricia’s sister, Marilyn Gifford, said it was bittersweet because her remains have still not been found.

“He had 45 years to return Patty’s remains to us, but he cruelly chose not to,” she said, reading from a statement.

“We never got a chance to lay her to rest in God’s arms. Without closure, every happy memory of Patty is immediately crushed by the tragedy of her murder.”

“Tonight’s execution was appropriate because Dennis Sochor was a lifelong brutal and sadistic man,” she added.

The devastated sibling pointed out that Sochor spent more than twice as long on death row as her sister got to live her entire life.

Patricia Gifford was celebrating the incoming New Year with a friend when she met Sochor and his brother, according to court records.

The four spent hours talking before the friend became ill and went to sleep in her car. Gifford then left with Sochor and his brother to get breakfast.

Instead of going for food, investigators say Sochor –– who grew up in Michigan –– stopped his truck in a secluded area and attacked Gifford.

He was later arrested in Georgia in 1986 on unrelated charges and extradited to Florida.

His brother told cops that Sochor was responsible for the teen’s disappearance, and Sochor himself confessed on tape to choking and disposing of her body.

He was convicted of first-degree murder and kidnapping in 1987, before being sentenced to death.

While strapped to a gurney on Tuesday, the warden asked Sochor if he had any final words.

Sochor said he was “deeply sorry” and thanked his loved ones for their support over the years.

He then commended his spirit to Jesus Christ before the drugs were injected through an IV in his arm at 6:03 p.m.

The prisoner was seen to be breathing heavily for about a minute before he started sputtering.

Sochor then went still for two minutes, leading the warden to look into his eyes, shake his shoulders, and yell his name. He did not get a response.

A medic was summoned and pronounced Sochor dead at 6:16 p.m.

Another 74-year-old inmate, Dusty Ray Spencer — who was just one week younger than Sochor at time of execution — was put to death in June.

Florida is also set to execute 80-year-old Dominick Anthony Occhicone later this month — who would be the state’s first octogenarian to be executed with a lethal injection in the state and the second oldest prisoner known to be put to death in modern US history.

The state has carried out 10 of the 16 executions conducted in the US so far this year — which is more than every other state combined.

With Post wires.