A man from South Carolina, convicted of a double homicide dating back to 2005, was executed by lethal injection on Friday marking the fourth execution carried out in the U.S. this week.

Stephen Stanko, aged 57, was declared dead at 6:34 p.m. local time (2234 GMT) at the state correctional facility in Columbia, according to a statement released by the South Carolina Department of Corrections.

In accordance with state law, Stanko was given the option to choose between three execution methods: firing squad, electric chair, or lethal injection. He opted for the latter

Stephen Stanko was found guilty of killing his girlfriend, 43-year-old Laura Ling, and Henry Turner, a 74-year-old acquaintance, in 2005.

He also attacked Ling’s teenage daughter sexually assaulting her and slashing her throat. She survived the brutal assault and later gave testimony that helped convict him.

In a final message delivered through his attorney, Stanko expressed remorse, saying he was “deeply sorry for the pain and loss” he had caused.

“Sorry will never be enough,” he added, “but that doesn’t mean it shouldn’t be said.”

Stanko became the fourth Death Row prisoner to be executed in the United States this week.

President Donald Trump, a vocal supporter of the death penalty, had called for its broader application on his first day in office, advocating its use in cases involving the most heinous crimes.

Just a day before Stanko’s execution, 61-year-old John Hanson was put to death by lethal injection in Oklahoma.

He was convicted of abducting 77-year-old Mary Bowles from a Tulsa shopping mall, killing her and a witness, Jerald Thurman.

At the time of his transfer, Hanson was serving a life sentence for bank robbery at a federal prison in Louisiana.

The Trump administration authorized his relocation to Oklahoma so he could face capital charges and ultimately the death penalty.

On Tuesday, two more executions took place in the United States. In Florida, 54-year-old Anthony Wainwright was executed by lethal injection for the 1994 murder of 23-year-old Carmen Gayheart, a nursing student and mother of two.

That same day in Alabama, Gregory Hunt, 65, was put to death using nitrogen gas after being convicted of raping and killing his girlfriend, 32-year-old Karen Lane, in 1988.

So far this year, the U.S. has carried out 23 executions: 18 by lethal injection, two by firing squad, and three using nitrogen hypoxia a method in which nitrogen gas is administered through a face mask, leading to death by suffocation.

The use of nitrogen gas has drawn international criticism, with United Nations experts condemning it as a cruel and inhumane practice.

Currently, 23 U.S. states have abolished the death penalty altogether, while three others, California, Oregon, and Pennsylvania, maintain official moratoriums on its use.