MIAMI, June 11, 2025 (AFP) - An Alabama man who murdered his girlfriend was put to death by nitrogen gas on Tuesday, with another man executed by lethal injection in the US state of Florida.

Gregory Hunt, 65, was pronounced dead at 6:26 pm Central Time (2323 GMT) at the Alabama state prison in Atmore.

He was executed by nitrogen hypoxia, which involves pumping nitrogen gas into a facemask, causing the prisoner to suffocate.

It was the fifth execution in the southern US state using nitrogen gas, which has been denounced by UN experts as cruel and inhumane.

Only one other US state, Louisiana, has used this method.

Hunt was convicted of the 1988 rape and murder of 32-year-old Karen Lane, whom he had been dating for a month.

In Florida, Anthony Wainwright, 54, was put to death by lethal injection at 6:22 pm Eastern Time (2222 GMT) at the Florida state prison in Raiford.

Wainwright was convicted of the 1994 rape and murder of Carmen Gayheart, a 23-year-old nursing student and mother of two young children.

Wainwright and an accomplice, Richard Hamilton, abducted Gayheart three days after escaping from a prison in North Carolina.

Hamilton was also sentenced to death for Gayheart's murder but died in prison.

A third execution this week is scheduled to take place on Thursday in Oklahoma, where John Hanson, 61, is to be put to death for the 1999 kidnapping and murder of Mary Bowles, 77.

Hanson's execution has been temporarily put on hold by a judge amid claims his rights were violated during a clemency hearing.

Oklahoma Attorney General Gentner Drummond has asked an appeals court to lift the stay to allow the execution to go ahead.

The fourth execution this week is to be carried out in South Carolina, where Stephen Stanko, 57, is to be put to death by lethal injection.

Stanko was convicted of the 2005 murders of his girlfriend, 43-year-old Laura Ling, and Henry Turner, a 74-year-old friend.

There have been 21 executions in the United States this year: 16 by lethal injection, two by firing squad and three using nitrogen gas.

The death penalty has been abolished in 23 of the 50 US states, while three others -- California, Oregon and Pennsylvania -- have moratoriums in place.

President Donald Trump is a proponent of capital punishment and called on his first day in office for an expansion of its use "for the vilest crimes."