Wendell Arden Grissom, has been by lethal injection nearly 20 years after he brutally a woman who was protecting her friend's

Grissom, aged 56, was found guilty in 2008 for the murder of Amber Dawn Matthews, 23, and for injuring her friend, Dreu Kopf, during a home invasion in Blaine County. The former lorry driver was sentenced to death in for fatally shooting a woman as she held a friend's newborn during a home invasion two decades ago. He died at 10.13am local time on Wednesday March 20 at the Oklahoma State Penitentiary.

Over two dozen friends and family members of Amber Matthews witnessed Grissom's execution and heard his final words: "I apologise to all of you that I've hurt," Grissom said while strapped to the gurney, an IV line affixed to his right arm. He added: "I regret so much that I've put that hatred in your heart for me.

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"It took him a total of 13 minutes to die, and it took him a total of two minutes to kill my best friend," said Dreu Kopf, who was shot multiple times by Grissom but managed to escape the house, reports .

Grissom and a homeless hitchhiker he picked up randomly decided to burgle houses in Oklahoma. Dreu Kopf and Amber Matthews were at home with Kopf's two daughters when Grissom came knocking. He laughed as he shot his way into the house, hitting Kopf in the head, wrist and hip.

Matthews grabbed Kopf's five week old daughter and ran into the room where Kopf's 19 month old daughter was sleeping. Grissom then entered the room where Matthews was hiding with the two children and shot her in the head as she cradled one of the girls. Kopf reported hearing Matthews scream and plead "please don't shoot me" before the shots were fired.

Fortunately, Kopf managed to escape in Grissom's truck and flagged down another vehicle for assistance. At the time, police stated that Grissom fled Kopf's home using her husband's four-wheeler. According to court records, Grissom and Johns were apprehended at a nearby café after locals reported seeing them.

In January, Oklahoma Attorney General Gentner Drummond urged the state's Pardon and Parole Board to deny Grissom clemency, describing him as a "cold-blooded killer".

Drummond stated: "Wendell Grissom took the life of a kind, vivacious 23-year-old who went into nursing to help people and died protecting two innocent children. Amber Matthews' monstrous murder demands that justice be carried out."

Before the execution, Kopf said: "Amber is always going to be 6 feet under and I will always be the girl that got shot. I'm probably going to always be nervous and scared. It's taken 20 years of my life that I've had to deal with him. It's a rollercoaster."

She added that she hopes his death will mark the moment she "will never think of him again."

During Grissom's trial, the devastating impact of Matthew's death on her family came to light. Her heartbroken father, Garry Matthews, opened up about his loss: "She was not only my daughter, she was my best friend. In and out of marriages, she was always there for me. The last restaurant we ate in, I can't go back. Everything that reminds me of her brings back the pain."