They say they are hoping to find items connected to the robbery in the city's northeast last October.
Maqsood Ahmed and a female employee were closing up his money-transfer business when they were attacked by two men.
Ahmed, who was 55, died in hospital after being robbed and stabbed.
The woman was uninjured.
Staff Sgt. Colin Chisholm says there are four persons of interest in the case who are not co-operating.
“Any little piece of evidence with respect to the robbery that we can tie back and put all the pieces together helps,” Chisholm said Tuesday.
He wouldn’t say what exactly searchers are looking for, but did reveal they are items which would have been in the bag Ahmed was carrying that night.
Anyone with information is asked to call police.