And the city's top cop says it will never happen again.
Last Thursday, Yellowknife's immigration officer took part in the road checks, looking for illegal aliens.
The spot-checks resulted in calls of racial profiling as some of the 10 people asked for proof of citizenship were taxi drivers.
The question that remains unanswered is what criteria the immigration officer used to target the 10 people who were asked for identification.
In a transcript of a press conference held in Ottawa Friday, Coderre said the immigration officer overstepped her bounds.
"That was the only time that they've done it. It was wrong. It was a mistake and case closed," he said.
Yellowknife RCMP Insp. Paul Richards said police asked the immigration officer to take part.
"She was there as a resource person. Our members were not targeting anyone in particular. We were targeting traffic violations. She was another resource in the event that our officers needed the resource," he said.
"I think that this was a singular event and it won't be repeated," Richards said.
He wouldn't comment on what criteria the immigration official used when asking people for proof of citizenship.
"Let me make it clear that there is a division between the RCMP and immigration. Concerning the policies of conduct for immigration officers we won't comment," he said.