brett robinson , 33 , facing 12 charges after allegedly letting an inmate out of his cell and engaging in sex acts between march and july last year .
allegedly brought him into the control room where she worked at washing county jail and had sex with him on his birthday under a blanket .
relationship continued and robinson wrote inmate a love letter saying he was ` a constant presence in my thoughts , fantasies and dreams '
was caught during an investigation into colleague jill curry , 39 .
curry was sentenced to four years and two months in prison last month for repeatedly sleeping with a sex offender at the same prison .
robinson hopes to plead insanity and was ` vulnerable , passive and gullible '