Man jailed after committing murder in fit of sexual jealousy

A man has been jailed for at least 23 years after murdering another man in a fit of sexual jealousy.

Kai Pennell, 35, stabbed Duane Keen, 47, at a flat in Blaenavon, South Wales, where a woman they had both previously been romantically involved with, Rebecca Phillips, was living.

Pennell, of Blaenavon, remained “obsessed” with Ms Phillips after they separated and grew increasingly jealous of Mr Keen, Cardiff Crown Court heard on Tuesday.

He stabbed Mr Keen in the chest after forcing entry to the flat in the early hours of the morning of October 17 last year.

Mrs Justice Stacey said: “You appeared unable to accept that she did not want to be in a relationship with you.

“You would not leave her alone and you became fixated on whether she was seeing anyone else, including her ex, Duane Keen.”

Cardiff Crown Court heard Pennell was a former partner of Ms Phillips but she had ended their romantic involvement in September 2025.

Mr Keen was also a former partner of Ms Phillips although the pair had separated in May that year.

Christopher Rees KC, prosecuting, said: “The prosecution case is that (Pennell) remained obsessed with her and burning with jealousy.

“Kai Pennell was motivated by sexual jealousy to murder Duane Keen.”

On the night of the murder, Pennell had bombarded Ms Phillips with “disturbing” calls and text messages, the court heard.

Feeling unsafe, she asked Mr Keen to come to her address, where they were both ambushed by Pennell, who forced his way into the property and stabbed Mr Keen in the chest.

He fled the scene but was located by police later that morning.

On Tuesday, Mrs Justice Stacey sentenced Pennell to a minimum of 23 years in prison and imposed an indefinite restraining order prohibiting him from contacting Ms Phillips.

She said: “In your twisted and self-piteous logic you told her that your murder of Duane was somehow her fault. The only person to blame for Duane’s murder is you.

“You were motivated by sexual jealousy and anger when you killed Duane and as a way to try and control and punish Rebecca for breaking up with you and remaining friends with Duane.”

Detective Chief Inspector Jitka Tomkova-Griffiths, of Gwent Police, said: “Kai Pennell killed Duane Keen in a jealousy-fuelled and violent attack.

“Taking a knife from his own property implied that he intended to cause serious harm when confronting Duane in the early hours of that morning.

“His actions had devastating consequences and Duane’s death has impacted the lives of his family, loved ones, friends and community.

“I’d like to pay tribute to the friends and family who have had to come to terms with Duane’s death and shown great strength throughout this difficult process.

“I know today’s sentencing will never bring him back. However, I hope this outcome brings some consolation and closure for them.”

Mr Keen was described in court as being “well-known” in the mixed martial arts (MMA) community but “first and foremost a family man”.

In a statement, his family said: “Although justice has been given, the life sentence will never be truly enough, as we the family have lost our loved one who will never have his life to live and we now have to live the rest of our lives without him.

“We the family would like to thank the police, CPS and all the team that have worked tirelessly on this case and have supported us throughout the past several months.”