Sean Mahan jailed for killing mother's lover in Balloch
A man who beat a stranger to death after catching him in bed with his married mother has been jailed for four years and eight months.
Sean Mahan launched a prolonged attack on 33-year-old Stewart McKellar after finding him with his mother, Lavina, 50, at the family home in Balloch, while his father was working offshore.
He then phoned a friend and said: "I think I have killed him."
The 21 year old admitted culpable homicide over the August 2014 attack.
Jailing Mahan at the High Court in Edinburgh, judge Lord Turnbull told him that the assault on Mr McKellar was a "gross over reaction" to what he had witnessed.
'Grief and despair'
He added: "You engaged in a sustained violent attack in which you repeatedly punched a man who did nothing but try to protect himself.
"You have left the victim's family in a state of grief and despair and there is nothing that I can do that will alleviate these circumstances.
"This was a sustained and uncalled for act of violence."
An earlier hearing was told that Mr McKellar had been out with friends at the Lomond Park Hotel in Balloch on 23 August when he met Lavina Mahan.
Prosecutor Douglas Fairley QC said Mrs Mahan described being "chatted up" by Mr McKellar before she invited him back to her house on Luss Road for a drink just after 02:00.
The court heard that her son Sean then returned home and barged through the door, shouting: "How could you do this to my dad?"
He punched Mr McKellar repeatedly during a 20-minute attack, and also slapped his mother on the head.
Mahan then phoned 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 found "clear signs of a disturbance" at the house along with a hysterical Mrs Mahan.
Mahan was later found by police at a friend's house, hiding in a cupboard.
He was asked about Mr McKellar, and said: "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."