The family of a British woman stabbed to death in France have said they 'have a hunch' who murdered her – after she was killed outside her home following a wine tasting event.

Karen Carter, 65, was attacked at the property in the village of Trémolat in Dordogne on April 29 last year, amid claims she was the victim of a jealous feud related to her love life.

She had been on the verge of divorcing her South Africa–based husband, Alan Carter, now 66, while seeing Jean–François Guerrier, a 75–year–old retired business executive who lived close to her French home.

But the love triangle also ignited the ire of Marie–Laure Autefort, a retired care worker, now 70, who was said to be 'madly in love' with Mr Guerrier.

Mr Guerrier had hosted a wine tasting party on the day Ms Carter died, and later followed her to her home in his car.

When he got there he found her lying in a pool of blood, before she was declared dead at the scene by emergency workers.

Mr Guerrier first said he was concerned that his lover had not telephoned him on reaching her house, which was just 10 minutes away from his.

He then told police he 'had come to spend the night at Karen's', leaked interview notes revealed.

Mr Guerrier later told detectives to investigate Ms Autefort.

On the anniversary of the murder, Reda Hammouche, the Carter family lawyer, has stated the family 'have a hunch' who was responsible.

But he explained they were 'leaving it to the justice system to work towards uncovering the truth' beyond rumours.

Both Mr Guerrier and Ms Autefort were arrested after the killing, before being released without charge.

Both vehemently deny any wrongdoing, and continue to cooperate with investigators.

Philippe Monribot, Ms Autefort's brother, has confirmed she was in love with Mr Guerrier, and deeply upset by his affair with Ms Carter, but said the thought of her murdering someone was preposterous.

'It's a catastrophe,' he said. 'The police messed up at the start of the investigation and when you get it wrong at the beginning, it's difficult to get it right afterwards.'

A police record stated in the aftermath of the murder: 'During his brief custody period, Jean–François Guerrier directed them to Marie–Laure Autefort, a resident of Trémolat who lives only about a ten–minute walk from the victim's home, cutting across the fields.

'He described her as a woman who had fallen madly in love with him the previous year, to the point of divorcing the father of her children after several decades of marriage.

'She was then terribly frustrated when she realised that this budding passion was not reciprocated.'

The words guaranteed Ms Autefort's arrest, but she is said to have provided a watertight alibi.

Both Ms Autefort and Mr Guerrier are among those who have given DNA samples to police, along with some 15 guests at Mr Guerrier's wine tasting party.

None provided a match to forensic evidence found at the crime scene, where the only apparent witness was Ms Carter's puppy, Haku, who remained in her car. The dog is now being cared for by Mr Guerrier.

The possibility of a contract killing is also being actively investigated.

No murder weapon has been found, meaning the killer could have got in and out of Trémolat very quickly, perhaps on a motorbike.

Mr Carter – who had four children with Ms Carter – has responded to locals putting him in the frame, suggesting he had organised the murder so as to take full control of the family's sizeable estate.

He said last summer: 'It's been extremely upsetting to hear what's being said, though more for our children and the rest of the family, than me.'

Jacques–Édouard Andrault, the Périgueux prosecutor who is leading the enquiry into 'pre–meditated murder' said: 'I can only confirm that the investigation is continuing actively.'

A friend of Ms Carter's previously told The Mail on Sunday she had seemed 'very happy in her new relationship' with Mr Guerrier.

She said: 'I've known Karen for a while.

'She seemed to be someone fully in control of her life, a strong businesswoman who had an air of authority about her.

'I heard that she was trying to divorce her husband in South Africa but he wasn't keen on that.

'Karen had apparently been in a relationship with Jean-Francois Guerrier for a few weeks. It was really early days.

'By all accounts she was very happy in that new relationship but she kept it quiet and was quite modest about it.'

A post-mortem examination revealed Ms Carter most likely 'tried to defend herself from a frenzied attack'.

She had been in a relationship with the former managing director for Fujitsu Services for 'several weeks', the state prosecutor's office said.

The investigation is concentrating on those who knew the victim amid suspicions she was killed by someone who held a 'grudge' against her.

Another close friend of Ms Carter said: 'She was the loveliest person you could meet. She didn't have any enemies, as far as I'm aware.

'There was no feud with anyone. Nothing was stolen so it couldn't have been a robbery. Nobody knows why she was killed. Everyone who knew her is in complete shock at what has happened. She was fantastic.'

The friend also denied suggestions Ms Carter was in a relationship with Mr Guerrier, adding: 'They were just friends, that is all. The idea that they were in some kind of relationship is nonsense. Everyone is friends with Jean-Francois in this village.'

But a neighbour claimed the killing was indeed a 'crime of passion'.

Ms Carter was said to divide her time between France and South Africa. She and her husband have owned their property, called Les Chouettes, for 15 years.

The farmhouse and barn sleeps 16 in total and is a popular holiday rental. The couple owned two other properties near Tremolat.

On Tuesday, Ms Carter had trained with her football team, comprising women aged between 50 and 70.

Later that evening, she attended a wine tasting soirée at Cafe Village – a bar which acts as a community hub, where she occasionally volunteered.

Before she left, Mr Guerrier asked her to call him when she got home so he knew she was safe.

But when no such call was made, he drove to Ms Carter's home and found her body.

Despite the best efforts of medics, she died at the scene from severe blood loss.