A Hapless Fraud

- “Now, stop bothering me! I'm in a hurry!” - exclaimed a woman out of a car window throwing her unlit cigarette towards the detective.

- “If you do not get out of the car at once, I will have to resort to extreme measures,” said detective Kronin, who appeared on the scene just at the right time.

- “Didn't you take a cigarette lighter from a demo car and leave the showroom nonchalantly!”

- “Nonsense! Indeed, I've just left the car dealer, but it was to have a look on a new brand car for myself that I popped into the place.”

- “Don't go telling lies,” said Detective Kronin. “Will you please come down with me.”

Question:

How will detective Kronin confirm his accusation?