James McArdle, 64, from Hamilton, Lanarkshire, admitted sexually assaulting the 74-year-old woman, who was suffering from Alzheimer’s disease.

Crown prosecutors told the High Court in Glasgow that Mr McArdle’s attack on the vulnerable victim – carried out on 4 Jan 2022 – was recorded in its entirety on a Ring doorbell camera.

The device had been installed in the woman’s home by family members to allow regular checks on her welfare. The victim, who lived alone with the support of carers, had been a customer of McArdle’s for some 20 years.

He was permitted entry to her home to clean the inside of windows.

Prosecutors said the footage clearly showed Mr McArdle repeatedly approach and assault the victim. The crimes were discovered shortly after he left the woman’s home.

A relative of the victim viewed the recording on their mobile phone and alerted the police.

At the High Court in Glasgow, McArdle was sentenced to four years and six months’ imprisonment.

His name was added to the sex offenders register indefinitely.

Katrina Parkes, national procurator fiscal for High Court sexual offences, said: “McArdle exploited and abused a frail woman in her own home. He was well aware of her illness and her vulnerabilities. His behaviour towards her deserves our utmost contempt.

“This despicable betrayal of trust was exposed by the vigilance of those who loved the victim and kept a watchful eye on her welfare.

“Their determination to ensure McArdle cannot offend in this way again has helped COPFS to bring him to justice and protect vulnerable members of society.”