A son walked in on his mother having sex with a boyfriend while his father legally married, was working away from home, offshore, before bludgeoning the man to death in cold blood.
Sean Mahan has pleaded guilty to culpable homicide for battering the man to death after finding him naked in bed with his married mother.
Sean Mahan discovered Stewart McKellar and his mother Lavina together while his father was working offshore.
The 21-year-old fatally attacked Mr McKellar at the family home in Balloch, near Loch Lomond before lashing out at Mrs Mahan.
Mahan then called a friend stating: “This guy was sleeping with my mum. I think I’ve killed him.”
Mahan now faces a lengthy jail term after he pled guilty at the High Court in Glasgow to the culpable homicide of Mr McKellar.
Mr McKellar died after being out with friends at the nightclub in the Lomond Park Hotel in Balloch on August 23.
The 33-year-old was described as “being in good spirits” and “enjoying the company”.
It was at the club he met 50-year-old Lavina Mahan, who was also out with a friend.
Prosecutor Douglas Fairley QC said: “She describes being ‘chatted up’ by Mr McKellar and asked him back to her house for a drink just after 2am.”
They headed to Mrs Mahan’s family home where she invited Mr McKellar upstairs as she was “worried someone would come in”.
The court heard her son then suddenly returned home in the early hours and found his mother in bed with Mr McKellar.
He barged the door open and yelled: “What are you doing? How could you do this to my dad?”
His father John Mahan was working offshore at the time.
The court heard there was then a “prolonged assault” lasting up to 20 minutes on Mr McKellar, which involved repeated punching.
Mahan then turned on his mother slapping her on the head and calling her “a slut”.
As a badly beaten Mr McKellar lay naked on the floor, Mrs Mahan managed to run away.
Mahan then called a friend and said: “Mate, you will need to come down. This guy was sleeping with my mum and I think I have killed him.”
Paramedics soon arrived at the house after being alerted to what had gone and discovered a hysterical Mrs Mahan.
Mr Fairley told the court: “There were clear signs of a disturbance, broken furniture and glass as well as items of male and female clothing on the bedroom floor.”
Attempts were made to save Mr McKellar, but he was pronounced dead.
Mahan was later found by police at a friend’s house hiding in a kitchen cupboard.
He asked about Mr McKellar and claimed: “I only punched him. What would you have done? My dad’s working offshore and I come home to find my mum in bed with someone else.”
Judge Lord Turnbull remanded Mahan in custody and deferred sentencing until next month for reports. – STV News