Arrested for driving a stolen car in Clearwater, Florida, Joseph Bravo Ramos was being booked into the Pinellas County jail when deputies asked him to step on a scanner.
The scanner, designed to find contraband on detainees, typically detects weapons, pills and drugs.
However, the X-ray scan last Thursday, found two necklaces coiled into a ball inside Ramos' midsection, the Tampa Bay Times reported.
Ramos admitted he swallowed the jewellery, which detectives determined had been stolen, the Pinellas County Sheriff's Office said.
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On December 10, a burglary was reported at a home on Palmetto Drive in Safety Harbour. No one was home, but several items were taken, including necklaces and the car.
The following day, police officers stopped Ramos for reckless driving and found the car he was in was stolen.
Ramos was taken to the Pinellas County jail on charges of grand theft and driving without a valid license. Officers also cited him for reckless driving, Clearwater police said.
But when Ramos was screened by the Sheriff's Office's SecurPass X-Ray, deputies saw a "large dark mass" near his stomach, officials said.
Concerned the chains could cause "significant health issues" for Ramos, doctors at Northside Hospital decided to surgically remove them, Gualtieri said.
If not for the medical concerns, the Sheriff's Office might have opted to "let nature take its course" instead, he said.
Doctors removed the two yellow-gold chains from Ramos on Thursday and he was returned to the jail the same day.
After the surgery, detectives showed the chains to the burglary victim, who identified them.
It is unclear when Ramos swallowed the jewelry, valued at about USD 450.