Former Sunshine Coast radio host Peter Lang found guilty of ...

A former Queensland radio host who was prominent on the Sunshine Coast during the 1980s has been found guilty of historic sex offences against a child. 

Peter Lang, 65, was a well-known radio personality at 4SS, now Mix FM, in the late 1980s when the offences were alleged to have occurred.

Jurors in the Maroochydore District Court trial retired just before 1pm on Tuesday and took one day to return their verdict. 

Lang was found guilty of three counts of carnal knowledge of a girl under 16 and two counts of indecent treatment of a girl under 16, all in relation to one victim.

The jury was dismissed in relation to the remaining four counts, that included rape, due to the jury being deadlocked.

Lang was also found not guilty of four counts of carnal knowledge of a girl under 16 and three counts of indecent treatment of a girl under 16.

He had pleaded not guilty to all 22 charges, including rape and indecent treatment of a child under 14.

The verdict comes after six charges relating to a second complainant were dismissed on Friday and one amended.

The court heard Lang was in his late 20s and the two girls were underage teenagers at the time of the alleged offences.

During his final directions to the jury, District Court Judge Glen Cash said the vital element in their deliberation should be about the beliefs Lang had regarding the alleged victims' ages at the time.

In her final summary on Tuesday, Crown prosecutor Rebecca Marks told the jury the alleged victims were honest and credible witnesses.

Ms Marks said it was understandable that the women had difficulties with their memories on some occasions.

"We're taking about events in the past," Ms Marks said.

Ms Marks on Monday said Lang abused his celebrity status and his age to satisfy his sexual interests in two underage girls.

While giving evidence on Monday, Lang was asked by the prosecution why he didn't confront one of the alleged victims about her age when it was brought up during a conversation that was secretly recorded by the police in 2021.

"I was mortified, numb," Lang said.

Ms Marks put it to Lang that he asked the two girls to meet at night in the grounds of two primary schools because it "aroused" him.

Lang strongly denied the account.

Ms Marks also suggested that Lang's assertion that he allegedly asked for one of the girls' age more than once indicated he believed the alleged victim to be underage.

Lang denied that, stating he asked because he wanted to be reassured.

Ms Marks suggested to Lang that he had a sexual interest in young girls, to which Lang replied, "Absolutely not".

During the proceedings, Lang's sister briefly took to the stand for the defence to give evidence relating to the year Lang moved to the Sunshine Coast.

Defence barrister Saul Holt later told the court there was a "profound change" in the dates given by one of the alleged victims.

Mr Holt said the alleged incidents in 1986 could not have happened because Lang was not on-air until 1988.

In his summary, Mr Holt said the prosecution's case had fallen apart when six charges were dismissed in relation to the second complainant.

Mr Holt said the evidence given during the trial proved Lang's assertion that he genuinely believed the alleged victims to be 16 years old.

He told the jury it was unbelievably difficult to judge a person's age.

"… particularly when you're talking about 13 or 14 years old, you're talking about a time when people change physically and emotionally," Mr Holt said.

The court last week heard Lang was not proud of the way he lived his life in the 1980s.

Lang admitted to having sex with the girls but told the jury they had both lied to him about their ages.

His former housemate appeared as a witness at the trial, recalling an incident in which the radio host had sent him to break up with one of the girls on his behalf.

The man described the girl as young and said she appeared uncomfortable and upset.

The jury also heard evidence from the mother and older sister of the second complainant, who had accused Lang of rape.

The sister told the court she had been involved in the initial call to Lang at the radio station, along with a friend.

"There was flirting and just laughing," the sister said. 

"He [Lang] asked us what we looked like and our ages."

But the witness told the court the host said something to her 13-year-old sister that shocked her.

She said she couldn't recall exactly what it was.

The second complainant's mother and sister comfort each other after leaving court.(ABC Sunshine Coast: Jessica Ross)

"Something that wasn't right ... something went too far and we just ended the call," she said.

The prosecution said Lang arranged during the call to meet the younger girl outside a Buderim school before leading her into the grounds and raping her.

Mr Holt asked the complainant's mother about her daughter's state of mind at the time.

The woman had separated from her husband and the girl had changed schools.

"Did you explain to the prosecutor that her attitude was, at the time when she 13, 14, terrible, and that she was dreadful and difficult," Mr Holt asked.

"She was," the mother agreed.

"And that she'd do anything to shock you," Mr Holt asked.

"She would ... but not in the way you're making it sound," the mother replied.

Former Mix FM chief executive John Williams (left) and former host Alan Doblo gave brief evidence during the trial. (ABC Sunshine Coast: Jessica Ross)

The trial also heard from former radio announcer Alan Doblo, to confirm the timeline of when Lang started at the station.

Mr Doblo said he didn't believe Lang was on-air until 1988.

Former Mix FM chief executive John Williams was also asked to recall the dates Mr Lang began working for the commercial radio station.

Mr Williams also believed Lang started in 1988.