A Brisbane man has accused police of pocketing a ring he stole, swallowed, and then passed on while in custody.

A diamond-swallowing thief who was ordered to undergo a colonoscopy to recover two engagement rings says his experience was more inconvenient than painful.

David William Watts, 50, was sentenced in the Brisbane Magistrates Court on Thursday after he pleaded guilty to one count of stealing and three unrelated charges.

He was ordered to cough up more than $11,000 in compensation and received a suspended six-month jail sentence.

Watts was arrested in late 2013 after snatching and swallowing two diamond rings from Crown Family Jewellers at Indooroopilly, in Brisbane’s west.

The court heard the forensic recovery process didn’t go as planned and one of the rings was lost.

Magistrate Noel Noonan said it should have been in Watts’ interest to retrieve the second ring, which he passed on during his 11 days in custody.

“For some bizarre reason … you then cleaned it, tied a bit of string to it, and then swallowed it again in the shower, where CCTV recorded suspicious behaviour,” he said.

Outside court, Watts accused police of stealing the first ring and said he re-ingested the second to keep it from officers.

He said he was treated badly in custody and police didn’t know how to approach the problem.

“They had me in a glass, y’know like Hannibal Lecter was in, a square thing with the glass. That’s how they had me man.”

Watts also alleged police had threatened to kill him.

The fate of the lost ring is now the subject of a police probe.

In sentencing, the magistrate took into account Watts’ early guilty plea and noted that the pensioner has had a “difficult life”.

“You’re hardly a serious criminal,” Magistrate Noonan said, soon after Watts’ mobile phone had rung in court for a second time.

The court was told Watts was sexually abused while in the Boys Town school for disadvantaged children, had been anticipating a payout and was “angry and depressed” at the time of the offence.

Watts said he wasn’t sure how he was going to pay the compensation.

“It’s gonna come out of my pension … so it’ll be even harder to live.”