The 36-year-old's constant stares began to unsettle the group, and they got up and moved to another part of the Vikings Club in Chisholm.

They didn't know it, but Kaczmarek had a paraphilic condition in which he obtained intense sexual gratification from touching women without their consent.

He has been variously diagnosed with autism, sexual deviancy, schizophrenia, and obsessive compulsive disorder.

Kaczmarek also had a history of indecent acts against women, and was still on a good behaviour order while at the club in October last year.

Later that night, the subject of his attention left her friends and walked out of the club alone.

She became frightened when she heard footsteps following her through the carpark.

Kaczmarek grabbed her from behind and tried to put his hands under her skirt.

She fended him off as he tried to lift her skirt up, and turned to see his face, recognising him as the man who had been staring at her inside the club.

Police later went to Kaczmarek's home, seizing his clothing and club card. They also obtained CCTV images showing Kaczmarek following the victim out.

He was charged with two offences, an act of indecency and unlawful assault, and pleaded guilty.

Justice John Burns sentenced Kaczmarek to 22 months behind bars on Tuesday, and set a non-parole period of 14 months.

Kaczmarek was found to be a high risk of sexual reoffending.

Justice Burns agreed with mental health reports finding the offender had schizophrenia and paraphilia, a condition in which individuals obtain gratification from atypical situations or individuals.

Justice Burns said mental illness had partially contributed to the offence, and reduced the inmate's moral culpability.

Kaczmarek's lack of empathy and remorse were also attributed to mental illness.

He will be eligible for release in December, but the sentence administration board has been advised to consider his progress in therapies and programs for alcohol and sexual reoffending before granting parole.