A man who is in a detention centre for allegedly swallowing a 1.7-carat diamond May 10 in Windsor, Ont., expelled a fake gem Friday.

Police said in a media release that Richard Matthews, 52, passed a cubic zirconia early Friday.

Matthews then underwent an ultrasound at Hôtel-Dieu hospital in the afternoon. It confirmed the presence of two more stones still inside his intestinal tract.

Police said, it is unknown when the two remaining stones will be expelled.

Matthews has been in police custody since he allegedly tried to steal the $20,000 gem from Precision Jewellers.

Windsor police said he has not yet passed the diamond that is said to be inside him. The man consented to the ultrasound to determine the location of the stone, if it's there.

The man has undergone several X-rays and police said they revealed multiple stones.

While all parties wait, the man has been held in a cell and given the food of his choice to keep his bowel movements regular. Police have been inspecting his movements as they happen.

The suspect has been known to both police and jewellers.

Jewellers Vigilance Canada, an Independent, non-profit association to advance ethical practices within the Canadian jewelry industry, had been circulating bulletins warning the accused may be visiting stores in Ontario.

In the first bulletin, JVC identifies the man as Richard McKenzie. Windsor police confirm he is the same man in custody.

Police acknowledge they have video of the alleged theft at Precision Jewellers.

Sgt. Brett Corey said police will not release the security video because it "has evidentiary purposes."