Woman went undercover to collect evidence and led police to the grave of man marked by a can of Red Bull after her fiance confessed he had mowed down charity cyclist and hidden the body with the help of his twin brother By Daily Mail Reporter Published: 00:20 BST, 21 August 2023 | Updated: 00:20 BST, 21 August 2023 e-mail View comments A woman who went undercover to help police catch her killer fiancé has spoken of the crucial role she played in bringing him to justice. Caroline Muirhead, 32, gathered evidence that helped to convict Alexander ‘Sandy’ McKellar after he knocked down and killed cyclist Tony Parsons. McKellar and his twin Robert tried to cover up the crime in September 2017 by burying the former Navy petty officer. Ms Muirhead met deerstalker McKellar, 31, through Tinder but just five weeks later he confessed to causing the 63-year-old cyclist’s death. Mr Parsons had planned to ride through the night to complete a 100-mile journey from Fort William back to his home in Tillicoultry, Clackmannanshire. Caroline Muirhead, 32, gathered evidence that helped to convict Alexander ‘Sandy’ McKellar after he knocked down and killed cyclist Tony Parsons McKellar and his twin Robert tried to cover up the crime in September 2017 by burying the former Navy petty officer Cyclist Tony Parsons was struck by a pick-up truck being driven by a drunk Sandy McKeller with Robert in the passenger seat Tony's body was discovered thanks to a can of red bull left at his burial site by Muirhead Police search a Highland farm at Auch Estate in connection with the disappearance of Tony Parsons on January 8, 2021 in Bridge of Orchy, Scotland The father of two, who had won a battle with prostate cancer, travelled north by train on the morning of September 29, 2017. But after 11pm, when he was last seen having a drink in the Bridge of Orchy hotel, he was struck by a pick-up truck being driven by a drunk Sandy McKeller with Robert in the passenger seat. READ MORE: The unmarked grave of a charity cyclist who was hit by a drink-driver and buried in the Scottish wilderness with the help of his twin brother - but was caught after confessing to his fiancée who told police where to find it Advertisement The brothers had been drinking in the same bar as Mr Parsons before they crashed into him on the A82 on their way back home to the 9,000-acre Auch Estate in Argyll. They decided to bury his body in a peat bog and lived with their secret for just over three years. Sandy McKellar admitted his crimes to Ms Muirhead in November 2020 as they discussed getting married. She told the Sunday Mail: ‘I was in shock, frozen almost. I didn’t know what to believe. This man I thought I could be with for the rest of my life had just told me he was a killer. I didn’t know what to do.’ After his confession, Ms Muirhead spent a month gathering information before dropping a can of Red Bull at Mr Parson’s shallow grave so it could be found by police, as the Mail reported last month. Ms Muirhead, a forensic pathologist from Glasgow, told how McKellar first appeared gentle and kind towards her, but his personality could change when he drank heavily. She recalled asking him in late November 2020 if he was OK after he visibly tensed when a police car drove past them one evening. She said: ‘I asked him, “What is it? What is going on? What is it you’re not telling me?”. I said if we were going to be together and be a team, he needed to tell me what was wrong and I’d support him. The widow of charity cyclist Tony Parsons, Margaret Parsons (left) and their daughter Victoria, arrive at the High Court for drunk driver Alexander McKellar's sentencing Mr Parson's son Mike (right) and his wife arrive at the High Court, Glasgow, for the sentencing of drunk-driver Alexander McKellar who killed his father with his car on September 29, 2017 The final journey of former naval officer and charity cyclist Tony Parsons Police officers search the valley on the outskirts of Tyndrum, Stirlingshire ‘He started having a panic attack. He was gasping and started wailing. Then he told me what he’d done… something that he’d got away with for years.’ He then took her to the site of the grave on the estate where he lived. Ms Muirhead said: ‘He pointed out where the body was and told me what had happened and how they (the brothers) had hit him, that it was an accident. ‘He said they hadn’t trusted the police, they’d had issues with them before and thought they were out to get them, so that’s why they didn’t go to the police.’ Both McKellars had been due to stand trial for murder, but appeared in court last month to plead guilty to lesser charges. Alexander admitted culpable homicide, while Robert pleaded guilty to attempting to defeat the ends of justice. They are due to be sentenced on Friday. Ms Muirhead is reported to be considering legal action against Police Scotland over claims she felt ‘coerced’ into spying on her ex after she alerted them to the grave. She is also said to have lodged multiple complaints against the force, with the Crown Office referring eight complaints to the Police Investigations and Review Commissioner (PIRC). A Police Scotland spokesman said: ‘It would not be appropriate to comment on these assertions as criminal proceedings have not concluded. There are a number of outstanding complaints which will be progressed at the conclusion of all criminal proceedings.’ The Crown Office and Procurator Fiscal Service (COPFS) said: ‘This case remains active until sentence. It would not be appropriate for COPFS to comment.’ Share or comment on this article: Woman went undercover to collect evidence and led police to the grave of man marked by a can of Red Bull after her fiance confessed he had mowed down charity cyclist and hidden the body with the help of his twin brother e-mail Add comment Comments 0 Share what you think No comments have so far been submitted. Why not be the first to send us your thoughts, or debate this issue live on our message boards. Add your comment Enter your comment By posting your comment you agree to our house rules . Submit Comment Clear Close Do you want to automatically post your MailOnline comments to your Facebook Timeline? Your comment will be posted to MailOnline as usual. No Yes Close Do you want to automatically post your MailOnline comments to your Facebook Timeline? Your comment will be posted to MailOnline as usual We will automatically post your comment and a link to the news story to your Facebook timeline at the same time it is posted on MailOnline. To do this we will link your MailOnline account with your Facebook account. We’ll ask you to confirm this for your first post to Facebook. You can choose on each post whether you would like it to be posted to Facebook. Your details from Facebook will be used to provide you with tailored content, marketing and ads in line with our Privacy Policy .