A Chorley grandmother who had an affair with an inmate while working at HMP Garth has been found guilty of misconduct in a public office.
Jurors in the case of Alison Sharples, 46, took just two hours and 14 minutes to convict her after hearing how a syringe with traces of the inmate's semen was found in her handbag.
Petite dark-haired Sharples, of Hamilton Street, Chorley, had denied misconduct in a public office by having an inappropriate relationship with inmate Marvyn Berkeley while she worked as an operational support officer at HMP Garth in Leyland.
She is expected to be sentenced at Burnley Crown Court on November 30.
Preston's Sessions House court had previously heard the syringe, with the inmate's semen in the bottom, was found in her handbag when she arrived for a night shift at the jail two years ago.
When quizzed, Sharples claimed she had used it to give Calpol to her granddaughter.
But prosecuting, Camille Morland told the court tests revealed DNA matched that of serving prisoner Marvyn Berkeley - or his twin brother.
Sharples former friend, Nicola Ball, gave evidence she was having an inappropriate relationship with Berkeley, and said Sharples had gathered the semen from a sample pushed under a cell door in a plastic bag.