Mom Reveals Her Son's Final Words Before He Was Reportedly Shot Dead by His Own Father While Protecting His Pregnant Fianceé

Harold Luster has been charged with one count of first-degree murder and one count of armed criminal action after allegedly shooting his son, Kevin Ward, police confirmed

• Harold Luster, 61, allegedly shot his son Kevin Ward, 26, dead on Christmas Eve, per a Facebook post shared by the Jefferson County Sheriff's Office
• Kevin was expecting a baby with his fiancée, Kaitlyn, in June, per KSDK
• "He was ultimately going to shoot Kevin's fiancée and Kevin sacrificed himself, he was the hero that night. He would rather die than have her and that baby taken," Kevin's mother, Katherine, told the outlet of Luster

A heartbroken mother has revealed the last words she heard her son say before he was allegedly shot dead by his father on Christmas Eve.

On Tuesday, Dec. 24, Harold Luster, 61, was said to have killed his son Kevin Ward, 26, after accusing him and his fiancée of "withholding information" about his wife’s alleged affair, PEOPLE previously reported.

After the Jefferson County Sheriff's Office confirmed in a news release shared on Facebook that Luster — of High Ridge, Missouri — had been charged with one count of first-degree murder and one count of armed criminal action, Kevin's mother, Katherine Ward, spoke about the alleged killing.

Kevin and his fiancée, Kaitlyn, were expecting their first baby in June, according to local NBC affiliate KSDK. 

Katherine, of St. Louis County, told the outlet that she heard Kevin in the background when Luster allegedly called her during the incident, saying "Dad, why are you doing this, I don't deserve this," as Luster beat his beloved truck.

"Kevin died with a gunshot to his forehead and his hands tucked in his pockets," Katherine said, per the publication. "He was ultimately going to shoot Kevin's fiancée and Kevin sacrificed himself, he was the hero that night. He would rather die than have her and that baby taken."

Katherine called Kevin her "go-to person," adding to the outlet, "My son was the best. He was a great kid that didn't deserve that night and I wish 1,000 times he never went down there. But me and him never would have thought this would ever happen. It's almost like I'm in a nightmare and I can't get out." 

"A senseless act took my baby away from me. I will never see him walk through my door and say 'Mom,' I won't have birthdays, Christmases. I will have to sit there and hold his baby for the first time because he won't be able to," she added to the outlet in the emotional interview.

According to a probable cause affidavit obtained by The Sun Herald, Kevin had been visiting his dad over the holidays with his fiancée. 

Luster and Kevin’s fiancée had reportedly gotten into an argument because the suspect believed his wife was cheating on him. He thought his son and Kaitlyn knew about the alleged affair, the outlet reported, citing the legal document.

During the alleged altercation, Kevin reportedly told his fiancée to get him a knife and advised her to “call 911 if something happened” between him and his father, the outlet said.

As the victim's fiancée began to leave, she heard him trying to calm his father down. “You’re not going to shoot her,” he said, to which Luster allegedly responded, “You want to get shot instead?” the Herald reported, citing the probable cause affidavit.

Luster was said to have fired a single bullet into his son's forehead, causing him to fall to the floor. He was pronounced dead at the scene, according to the Herald.

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Kevin's mother, Katherine, told KTVI, “He took an innocent boy’s life. A 26-year-old that was going to be a father. He took his life over something selfish.”

”If I could have (Kevin) here now and I could get one last talk to him, I’d tell him thank you; he saved that baby that night. He was so happy to be a first-time father, but he’ll never get that chance,” she said, per the outlet.

Katherine — who had been preparing snacks for her son at the time of his death — told KSDK, "My son cannot breathe, my son cannot walk, my son cannot see, my son is not here no more. Why should (Luster) get the pleasure of sitting, even though it's a jail cell, he's still alive, and I want him to suffer every day at that memory... As far as justice, he deserves life."

Luster pleaded not guilty on Thursday, Dec. 26, per the outlet, and is expected to appear in court for his bond review hearing on Jan. 3.

The Jefferson County Sheriff's Office didn't immediately respond when contacted by PEOPLE for additional information.