A man who brutally murdered his partner leaving her with car crash-like injuries after she had sex with his friend has been jailed.

James McCarten flew into a rage when he discovered Anna Rosenberg, 43, in his bedroom with his lifelong friend Alan McLean at his flat in Glasgow in May last year.

The killer left Ms Rosenberg, the daughter of a university professor, with 122 injuries after battering her to death.

The judge said her injuries were similar to those suffered by car crash victims.

McCarten, 51, returned to court on Tuesday to learn his fate and was sentenced to 15 years in jail for the murder.

Judge Kenneth Maciver QC said he was "forced to the view that this was a sustained, violent and brutal attack" and that the "murderous attack on Ms Rosenberg was carried out wilfully and cold-bloodedly for the purpose of punishing her".

He added: "I am bound to observe that you have previous convictions for violence and a previous conviction which has a domestic aspect to it."

After the attack, McCarten, left his flat in Maryhill, Glasgow, to watch a boxing match.

During his trial last month, he denied being a murderer and tearfully told the jury how he had loved Anna "so much" and had planned to marry her.

The trial heard how McCarten had been dating Anna for around 18 months. The mother had a house in Bearsden, East Dunbartonshire, but often spent time at her boyfriend's flat.

She was described as a keen gym-goer who would "not harm a fly".

Last year, McCarten allowed fellow builder Alan McLean to stay with him after he had split from his lover.

The 62-year-old told how he and the mother had sex in McCarten's bed while he was out on May 2 last year.

The pair were stunned when they suddenly heard McCarten return home. He arrived to find his friend hastily trying to put his clothes on while a terrified Anna lay in the bed.

McLean recalled: "He was shouting and bawling 'how could you do this to me?' Anna kept saying she was sorry, she was crying. James was upset but that was understandable."

He then kicked his friend out before launching a murderous attack on Anna. He repeatedly punched and kicked his petrified lover, leaving the flat covered in blood.

The trial heard Ms Rosenberg, who he also tried to throttle, suffered 122 injuries including multiple fractured ribs. McCarten went on to walk out his flat to watch a boxing match at a friend's house.

McCarten claimed it was the next day when he returned that he realised Ms Rosenberg was dead. In a 999 call, he said his partner was "not right" and "would not wake up".

The court heard he tried to clean up the property and put clothes on a naked Ms Rosenberg

McCarten said he got a "terrible shock" when he walked in on his friend and Anna, adding: "I thought: How could two people who are meant to love you do that?"

Prosecutor Tim Niven Smith put to him that Anna had been "pummelled to a pulp", adding McCarten was someone who appeared "easily riled".

Judge Maciver told McCarten on Tuesday as he sentenced him to life in jail that his victim "lived on for a period after this attack and perhaps for up to half an hour after it".

He added: "During that period, when it must have been obvious that she was dying a slow and painful death, you did nothing to assist and within a couple of hours thereafter you changed clothes and left the house to watch, of all things, a boxing match.

"You thought nothing of her condition, performed no checks on her, and when you did return to the house the next day after drinking with friends, your first thought was to exculpate yourself, and you began crude and ultimately inept and hopeless attempts to deflect responsibility from yourself and raise issues of accident."

He added: "You attempted to clean up the blood and the bedding, and you dressed and moved her body and you gave the emergency services and the police a false account of what had happened to her.

"Allied to your conduct the night before, this demonstrates a callous and heartless disregard for her and a selfish desire to avoid responsibility for the savage onslaught of violence which brought her life to an end."