Ketch moved beside the man and nodded at the doctor. “Why do you think that, sir?”

“Well.” The professor pulled out a pen to use as a pointer. “If I were setting a pipe down, the nearest step at my height would be the fourth. For you, I’d guess you’d leave it on the fifth. The last thing anyone holding a bomb would want to do is let the bomb drop from his hand. Plus, a right-handed person would naturally place something a bit to the right, just as a left-handed person would place it to the left. Whoever did this was probably in a hurry and would not take the time to center the pipe on the step.”

Hank gave up being irritated at the civilian butting in and started being interested. “Anything else?”

“Well, yes, there is. Whoever placed the bomb raised his foot to the first step as he leaned forward. See the mud.”

“How do you know it was our bomber?”

The professor straightened. “I would have noticed the mud on the step when I left yesterday, and it’s very unlikely anyone would go up my steps. The girl who smokes would not have mud on her shoes.”

Hank thought of asking what kind of freak notices a bit of mud, but both Ketch and Pecos were leaning down to look at the evidence.

Hank grudgingly added, “Anything else, Professor?”

The thin man looked shy, as if he was uncomfortable being the smartest one in the room. “The mud is brownish red. River mud. And it is still damp, not dry, so the bomb was placed less than an hour ago. It is likely the man walked up from the river behind the pharmacy.”

“One last question, Dr. Monroe. Is there anyone you know who would wish to harm you?” Hank asked.

To his surprise, the doctor hesitated. “No,” he finally answered.

Hank thought of himself as great at his job, but this teacher, with probably no police training, had proved him wrong. He hadn’t been looking close enough. “Chemistry teacher, right?”

“Right.”

“You ever work in a lab? Do forensics, maybe?”

“No, but I do read about it. Before I made tenure and hit forty, I dreamed of investigating crimes.”

“You’d be good at it, but this wasn’t a bomb. It was just set up to look like one. My guess is the bomber was just trying to distract us, or maybe someone wanted to have some fun playing copycat. The real bomber was at the hospital. The copycat here.”

Hank handed Benjamin the bag into which he’d put the fake bomb. “Professor, could I interest you in taking a look at this? We’ve sent five just like this one to the lab and gotten no clues. It’s a long shot, but somehow I wouldn’t be surprised if you notice something we missed.”