Phillip Carey, 48, pleaded guilty to raping the woman, who suffered from dementia, when he appeared at Preston Crown Court.
The Crown Prosecution Service (CPS) said the woman’s family became concerned after they noticed that her behaviour had changed.
They said she had grown fearful, wouldn’t allow physical contact and began pleading with them not to leave during visits, saying “don’t leave me, they will hurt me”.
The family became so concerned that they installed a covert camera in her room to try and discover what was causing her so much distress.
One day, soon after installing the camera, they were looking at the live feed when they saw Carey enter her room.
It was then that they saw, to their horror, Carey rape and sexually assault their beloved relative.
They immediately called police and he was arrested.
The CPS produced forensic evidence, which along with the camera footage, meant he had no option but to accept his guilt.
Carey was jailed for life with a minimum of 10 years.
Senior Crown Prosecutor Sophie Rozdolskyj said: "Carey abused his position of trust and targeted a vulnerable woman whom he should have been caring for.
"I am grateful to the victim’s family who have shown great strength throughout the Court proceedings.
"I hope today’s sentence provides them with some comfort, knowing Carey has been brought to justice for his actions."
DI Chris Naidu of Lancashire Police added: "Carey worked in a position of trust which he abused in the most despicable way.
"We welcome the sentence which reflects the seriousness of his crime and we commend the victim and her family for their dignity and strength throughout the investigation and court case."
Statement from the family
Speaking after Carey was sentenced to life in jail, the victim's family said: "Our elderly relative has gone through a horrific ordeal at the hands of someone we trusted to care for her.
"We had noticed her behaviour had changed, she became withdrawn, wouldn't hug or kiss us and she didn't want us to go when we were leaving.
"And on a couple of occasions she said things that worried us, suggesting she would be punished. We were concerned that maybe someone was being unkind or too rough with her so we decided to install a hidden camera in her room so we could see what was happening.
"We were shocked and horrified, never imagining that we would see her being abused and raped in her own room. We called the police and their response was brilliant.
"This whole episode has been very distressing to all our family. Our lives have changed as we struggle to come to terms with what happened.
"We are truly grateful as a family at the way we have been supported throughout this ordeal by the police and the other people in the team.
"We would like to say to others with elderly loved ones in care... Listen to what they are saying and be aware of behaviour changes.
"If you think there could be something happening to them do something about it.
"We are thankful that Mr Carey has been given a life sentence and that he will not be allowed to harm anyone else."
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