Cornwall Constable Tommy McKay told the CBC: "My initial thought was, 'I'm going to have to find out where she got this vehicle from, or my God, how am I going to put cuffs on this elderly female'".
The woman accidentally stole his auto after driving to Walmart right after picking up her rental Nissan Sentra from the local Enterprise Rental vehicle.
Police say both cars used fobs, which means they don't require a key to start the auto and it turned out the owner of the stolen Infiniti had left his key fob inside the vehicle.
It turns out the vehicle she thought was her rental was actually a 2015 black Infiniti QX50, a hatchback - which was obviously not the sedan she had originally rented.
Police say that both of these cars use key fobs to unlock and start the vehicle. The rental vehicle manager examined the woman's keys and noted that, in fact, she had rented a Nissan Sentra, while the keys in her possession belonged to a Nissan Infiniti.
This allowed the woman to drive off, completely unaware that it wasn't her rental. And she didn't realize her mistake for another two weeks.
Together, they returned to the Walmart she had visited shortly after making the rental.
The man whose auto was stolen came into the same Enterprise to rent a vehicle after realizing his auto was no longer in the Walmart parking lot.
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The keys she turned in belonged to a Nissan Infiniti rather than a Sentra, leaving the manager "slightly confused", said police.
Upon returning the auto the woman explained her frustrations with the vehicle rental agency.
At first, he tried to tell her that the company didn't even rent that model - but she was having none of it.
"She was upset because the ashtray was dirty, there were papers in the glove box, and there were golf clubs in the back". After all, she had no inkling she'd stolen the auto she was driving. The owner said he had ducked into Walmart and returned to find his vehicle missing from the parking lot, according to police.
"Once inside, the woman spoke to the manager and commented about how unkept the inside of the vehicle was and the fact that there was a set of golf clubs in it as well", reads a Facebook post from the Cornwall police explaining the mixup.
There were no official charges so this story has a happy ending.
Soon after, police received a report about a black Nissan Infiniti that had been stolen in the same parking lot.