Before pleading guilty to his "foolish" part in a prison riot, Emerson John Mau was taken to be searched as authorities questioned if an offence was committed in court.
Court officials were unsure if Mau was handed something by a member of the public and whether he might have ingested something.
Mau was in the Brisbane District Court on Friday to be sentenced with murderer Simeon Frederick Blair - who appeared by video link from the Maryborough jail - over a riot at Woodford Correctional Centre last year.
Before the judge entered court a person in the public gallery approached Mau in the dock and was spoken to by Corrective Services officers.
Almost immediately Mau had his mouth open and appeared to be choking on something in his throat before officers gave him water.
Proceedings were delayed while the 25-year-old was taken to be searched.
Prosecutor Jane Shaw told Judge Leanne Clare there was "apparently an exchange".
"I'm concerned an offence has been committed in the courtroom," Ms Shaw said, adding the person involved left immediately.
"The defendant in the courtroom has been searched to a limited extent but if something has been internalised ... there's an issue of rupture if there is anything."
Judge Clare instructed staff to ensure courtroom video was saved and the sentence continued.
Blair initiated the riot in the Woodford prison's exercise yard on May 5 last year by ripping a phone off the wall and swinging the handset.
He smashed tempered glass while Mau used grills from a toaster to damage windows and another person caused damage with a wheelie bin.
In the 25 minutes until authorities had control of the jail five prisoners caused more than $6000 of damage.
Mau returned to his cell on the instructions of officers but chemical munitions had to be used against Blair, who is serving a life sentence for the murder of Cleveland Clay in Maryborough in 2012.
The 31-year-old's parole release date has already been deferred by six months for destroying prison property and threatening officers on another occasion.
Mau's nine-page criminal history includes a conviction for pinning a police officer against a car while trying to flee in a stolen vehicle.
His barrister Sarah Cartledge told the court Mau fell into the wrong crowd and was easily influenced.
"In relation to his involvement in the riot he explains it as quite foolish and he regrets getting involved at all."
Mau followed what other prisoners were doing after arriving near the end of the riot and complied with instructions to return to his cell, Judge Clare said in sentencing the men, who both pleaded guilty.
Judge Clare sentenced Blair to 15 months behind bars to be served concurrent with his life sentence, and deferred his parole eligibility until December 2029.
Mau was handed a 12-month jail term to be served in addition to an earlier suspended sentence.
He is immediately eligible for parole due to time already served.