December 24, 2014 
A fuming son who caught his married mum in bed with a naked stranger battered the man to death in a fit of rage.
Sean Mahan also attacked his mother, slapping her in the face and branding her a “slut” after he discovered her in bed with Stewart McKellar.
His father was working away at the time, and the raging 21-year-old burst into the bedroom at the family home in Balloch, near Loch Lomond, and launched into a frenzied attack.
After battering the naked Mr McKellar around the room, Mahan called a friend and told them: “This guy was sleeping with my mum. I think I’ve killed him.”
Mahan now faces a lengthy jail-term after he pleaded 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 popular 33-year-old was described as “being in good spirits” and “enjoying the company” in the club, where he later met 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 the pair started kissing.
She invited Mr McKellar upstairs as she was “worried someone would come in”.
But, the court heard her son then suddenly returned home in the early hours and found his mum 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 mum 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.
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.
McKellar
Sean Mahan
Diamond Celebrities 
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