Whose name did the Inspector write down?

Will Ketchum settled into his chair as Sergeant Zupp came into his office. “‘Have all three arrived, Hans?” he asked.
Sergeant Zupp nodded. “They all agreed to come and answer a few questions. The storeowner objected at first, but the cab driver and the painter were willing enough.”‘
Inspector Ketchum looked pleased. “If one of them is passing the counterfeit bills around, this could be our first real lead in this case. I’ll talk to them altogether. I’ve read their statements so far. Tell them to come in.”
The Sergeant brought the men in and introduced them as Mr. Sales, the store owner, Mr. Brush, the painter, and Mr. Haack the cab driver.
“Gentlemen,”‘ said the Inspector, when all were seated, “the bank informs us that they found four counterfeit dollar bills among the cash deposited by Mr. Sales last Wednesday. They were easy to spot because they were all new bills, and they all had the same number on them. Mr. Sales, you say four new bills and one old one were handed to you by Mr. Brush that morning-and those singles were the only new bills among the cash you deposited?”
“Correct,” said Mr. Sales. “I might have noticed there was something unusual about them if I hadn’t handed over the counting of the day’s take to my wife while I answered a phone call from a business friend.”
“‘Mr. Brush,” said the Inspector, “you say that if you had any counterfeit bills in your possession, you must have gotten them in your change from, the cab driver?”‘
“Must have,” answered the painter. “They looked okay to me when I paid for the groceries. But I only had six dollars on me – a five-dollar bill and a single. I handed the driver the five-dollar bill-I remember-because I’d jotted down a telephone number on it that I didn’t want to forget. The next time I spent any money was in Sales’ store, and then all I had left was some loose change till the bank opened.”
Inspector Ketchum turned to the cab driver. “Mr. Haack, you say you don’t remember much about Mr. Brush’s trip from the station because you were running late and had to stop for gas before you could meet the next train. But Mr. Brush didn’t see your tank being filled.”
“‘Of course not,” said the cab driver. “I just got a few dollars worth at a self-service station right after I dropped him off, ‘ and I made up for the lost time.”
“‘Thanks for your time, gentlemen,”‘ said Inspector Ketchum, “I may be grateful for it later on.”
After the Sergeant showed the three men out, Inspector Ketchum handed him a slip of paper with a name written on it. “That man was lying, Hans,” he said. “Keep an eye on him.”
Whose name did the Inspector write down?