Brad William Simpson has previously masturbated on buses, in a library and on a footpath.

Brad William Simpson has previously masturbated on buses, in a library and on a footpath. Rachel Lang

A SERIAL public masturbator's offending has exhibited signs of escalating.

Mackay flasher Brad William Simpson's case was heard in Brisbane Supreme Court on Friday.

The man, in his late 30s, is in custody after more than a decade of performing lewd acts in public.

Among his victims in recent years were children.

Justice Debra Mullins said she had considered a psychiatrist's report.

The report persuaded the judge there were reasonable grounds for believing Simpson was a serious danger to the community.

The court heard there were concerns Simpson's offending had escalated - a contention that was not disputed in court.

The judge said Simpson had a diagnosis of exhibitionism and "alcohol abuse and possible dependence”.

Simpson has previously masturbated on buses, in a library and on a footpath.

In 2005, Simpson was sentenced for masturbating at women who passed his Mackay home.

In 2013, he appeared in Mackay Magistrates Court for public masturbation.

Bus indecencies occurred in 2013 and 2015. A girl aged 14 saw the first incident.

In 2015 a mother with her two-year-old child witnessed the second of those incidents.

In 2015, Simpson pleaded guilty to indecent treatment to children for exposing himself to two sisters at the Mackay library.

The victims in that case were 13 and 15.

In Queensland, jailed sex offenders due to be released can be placed on supervision orders, released on parole with supervision or given continued detention.

Friday's matter was a preliminary hearing and the next hearing was pencilled in for May 8, 2018.

-NewsRegional