A Wigan pensioner was sexually attacked in her own home by a man pretending to be a trainee doctor.
The 89-year-old woman was brutally assaulted by a man who regularly delivered her medication to her flat in Ashton.
Daniel Simonetti, a Jehovah's Witness, let himself into the old lady's home uninvited at 4.30pm on March 11 this year and, without bringing her medication, locked the door of her Ashton home and molested her.
Liverpool Crown Court heard that Simonetti, 31, had indecently assaulted a four-year-old girl 13 years ago. He never appeared in court over that, as the police gave him a caution.
Jailing Simonetti indefinitely, Judge John Roberts branded him "dangerous to vulnerable females" and said he found it remarkable that he was not prosecuted for the first offence.
Judge Roberts said that Simonetti had caused the pensioner "immense pain" during the serious sexual assault.
He imposed an indeterminate sentence and ordered him to serve at least three years but warned it would be up to the Parole Board to decide when and if he should be released. He also ordered him to sign on the Sex Offenders Register for life.
Keith Sutton, prosecuting, said: "He said he had come to take urine and was a trainee doctor." He carried out a serious sexual assault, causing his victim to cry out.
Mr Sutton said: "Simonetti pretended to talk to a medic on his phone and then went into her bathroom. He came out after a few minutes and then returned to the bathroom locking the door."
A neighbouring friend called at the flat and found the door locked. Simonetti let her in and he talked to them both before leaving, said Mr Sutton.
After the victim said what happened, the police were called and she was medically examined. She was found to have bruises and swelling.
Simonetti was arrested two days later. Simonetti, of Roper Street, St Helens, denied rape, which was dropped, but admitted assault by penetration. He has no previous convictions.
Defence barrister Paul Treble said Simonetti, who is deaf, was contrite and regretful. Mr Treble said: "He accepts it was a terrible offence."