“Where did she sit?” Sergeant Sellers asked.
Surprise was on Belder’s face. “I don’t get you.”
“When she was here.”
“Oh, over in that chair, the one Mrs. Cool’s sitting in.”
“That’s pretty well over at the far end of the office,” Sellers said. “Take a look out, Bertha, and tell me what windows you can see across the street.”
“I’m afraid I don’t understand,” Belder said. “What bearing does that have on the case?”
Sergeant Sellers explained patiently. “The person who wrote that second letter must have been able to see what was going on here in the office when Dolly Cornish called. I notice there’s an office building across the street. It’s not a wide street. Along in the afternoon, the light would be just right so a person standing in an office across the street could see in here.”
Belder frowned for a moment, then his face cleared. “By George, that’s an idea! You think this person was spying on me from an office in the building across the street?”
Bertha Cool said, “Why monkey with that stuff? You have the answer right here in your office.”
Sellers frowned for her to keep quiet, suddenly switched his point of attack.