Atmore, Alabama - A man was put to death by nitrogen gas in Alabama, one of two executions carried out in the US on Thursday.

Geoffrey West (50) died at 6:22 PM CT as he was executed for the 1997 murder of Margaret Berry, a 33-year-old gas station clerk and mother of two, during a robbery in the town of Attalla.

In a statement released by his attorney, West apologized and said he'd been confirmed as a Catholic on Wednesday, adding, "I urge everyone, especially young people, to find God."

Berry's son had opposed West's execution, saying it would "only add to the pain" he has experienced since his mother's killing.

Blaine Milam (35) was put to death by lethal injection around 20 minutes later in Texas for the 2008 killing of Amora Carson, the 13-month-old daughter of his girlfriend, during an "exorcism."

According to court documents, the child was "beaten, strangled, sexually mutilated, and had twenty-four human bite marks covering her entire body in what the medical examiner called the worst case of brutality he had ever seen."

In a final statement, Milam thanked the state corrections department for allowing him to join a faith-based program on death row. "I love you all, bring me home Jesus," Milam said, according to the department.

Milam's lawyers had sought to halt his execution on the grounds he is intellectually disabled but the appeals were rejected by the courts.

Milam's case was among those featured in a 2013 Werner Herzog documentary called On Death Row.

There have been 33 executions in the US this year, the most since 2014, when 35 people were put to death. Florida has carried out the most executions – 12 – followed by South Carolina and Texas.

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 on his first day in office called for an expansion of its use "for the vilest crimes."

Trump signed a presidential memorandum on Thursday directing federal prosecutors to seek the death penalty in Washington, the nation's capital, in appropriate cases.