Who is the robber?

Detective story 

I'm Colin Columbo, top detective. Last week the police asked me to help them investigate a robbery. 'Someone has stolen a very expensive trophy from a billionaire's house. We need your help!' I took my gloves, went by skateboard and hurried to the house. I looked for clues and found some crumbs.'Who's in the house? I asked the billionaire. 'My manager, my cook, my waiter, my gardener, my chauffeur and my cleaner,' replied the billionaire. I questioned the suspects, then I searched the house. 'I know who the robber is,' I said. 'I've found the stolen trophy! It's the cleaner!'

 - The end -