?No shit. What did Bergeron say??

?He?s on vacation until next Monday.?

?Cheese, that?s beautiful. Kind of like your false starts, eh? What do you want me to do??

?Find a piece of plain Styrofoam and get Tanguay to bite down on it. Don?t stick it too far into his mouth. I just need the front six teeth. Have him bite edge to edge so you get nice clean tooth marks, one arch on each side of the plate. Then I want you to take the Styrofoam downstairs to Marc Dallair in photography. He?s way in back, behind ballistics. You got that??

?Yeah. Yeah. How do I get Tanguay to agree to this??

?That?s your problem. Figure something out. If he?s screaming innocent he should be delighted. ?

?Where am I supposed to come up with Styrofoam at four-forty in the afternoon??

?Go buy yourself a bloody Big Mac, Bertrand. I don?t know. Just get it. I?ve got to catch Dallair before he leaves. Get moving!?

Dallair was waiting for an elevator when my call came. He took it at the reception desk.

?I need a favor.?

?Oui.?

?Within the hour Jean Bertrand will bring bite mark specimens to your office. I need to have the image scanned into a Tif file and sent to me electronically as soon as possible. Can you do that??

There was a long pause. In my mind I could see him glance at the elevator clock.

?Does this have to do with Tanguay??

?Yes.?

?Sure. I?ll wait.?

?Angle the light across the Styrofoam as close to parallel as possible to really bring the marks out. And be sure to include a scale, a ruler or something. And please make sure the image is exactly one to one.?

?No problem. I think I have an ABFO ruler here somewhere.?

?Perfect.? I gave him my e-mail address and asked him to call when he?d sent the file.

Then I waited. Seconds crept by with glacial slowness. No phone. No Katy. The digits on the clock glowed green. I heard them change. Click, click, click as the rotors turned.

When the phone rang I grabbed it.

?Dallair.?

?Yes.? I swallowed and the pain was excruciating.

?I sent the file about five minutes ago. It?s called Tang.tif. It?s compressed, so you?ll have to unencode. I?ll stick here until you?ve downloaded, to be sure there?s no problem. Just send a reply. And good luck.?

I thanked him and hung up. Moving to the computer I logged into my mailbox at McGill. The Mail Waiting!!! message glowed brightly. Ignoring other unread mail, I downloaded the file Dallair had sent, and returned it to its graphic format. A dental imprint arched across the screen, each tooth clearly visible against a white background. To the left and below the impression was a right-angle ABFO ruler. I sent Dallair a reply and logged off.

Back in the imaging program, I called up Tang.tif and double-clicked it open. Tanguay?s impression filled the screen. I retrieved the bite mark in the Rue Berger cheese, and tiled the two images side by side.

Next I converted both images to an RGB scale, to maximize the amount of information in the pictures. I adjusted tone, brightness, contrast, and saturation. Finally, using the image editor I sharpened the edges on the Styrofoam impression as I had with the indentations in the cheese.

For the type of comparison I planned to try, both images had to be to the same scale. I got out a needle point caliper and checked the ruler in the Tanguay photo. The distance between hash marks was exactly one millimeter. Good. The image was one to one.

There was no ruler in the Berger photo. Now what?

Use something else. Go back to the full image. There has to be a known.

There was. The Burger King cup touched the bowl adjacent to the cheese, its red and yellow logo clear and recognizable. Perfect.

I ran to the kitchen. Let it still be here! Throwing open the cabinet doors, I rummaged through the trash under the sink.

Yes! I washed off the coffee grounds and carried the cup to the computer. My hands trembled as I spread the calipers. The upright arm of the logo B measured exactly 4 millimeters across.

Selecting the resize function in the image editor I clicked on one edge of the B on the Rue Berger cup, dragged the cursor to the far border, and clicked again. Having chosen my calibration points I told the program to resize the entire image so that the B measured exactly 4 millimeters across at that position. Instantly the picture changed dimension.

Both images were now one to one. I looked at them side by side on the computer screen. The impression Tanguay had given showed a complete dental arch, with eight teeth on each side of the midline.

Only five teeth had registered in the cheese. Bertrand was right. It was like a false start. The teeth had gripped, slid, or been retracted, then bitten a chunk from behind the mark I was now seeing.

I stared at the trail of indentations. I was sure it was an upper arch. I could see two long depressions to either side of the midline, probably the central incisors. Lateral to them were two similarly oriented but slightly shorter grooves. Farther out, on the left of the arcade, was a small, circular dent, probably made by the canine. No other teeth had registered.

I ran my sweaty palms down the sides of my shirt, arched my back, and took a deep breath.

Okay. Position.

Choosing the Effect function, I clicked on Rotate, and slowly maneuvered Tanguay?s dental impression, hoping to achieve the same orientation as the mark in the cheese. Click by click I rotated the central incisors clockwise. Forward, then backward, then forward again, a few degrees at a time, my anxiousness and clumsiness prolonging the process. It took an entire growing season, but at last I was satisfied. Tanguay?s front teeth lay at the same angle and position as their counterparts in the cheese.

Back to the Edit menu. Stitch function. I selected the cheese as the active image and the Tanguay impression as the floating image. I set the the transparency level at 30 percent, and Tanguay?s bite mark grew cloudy.

I clicked on a spot directly between Tanguay?s front teeth, and again on the corresponding gap in the cheese arcade, defining a stitch point on each image. Satisfied, I activated the Place function, and the image editor superimposed Tanguay?s bite mark directly over that in the cheese. Too opaque. The cheese trail was completely obliterated.

I raised the transparency level to 75 percent, and watched the Styrofoam dots and dashes fade to ghostly transparency. I now had a clear view of the dents and hollows in the cheese through the impression made by Tanguay.

Dear God.

I knew instantly the bites were not by the same person. No amount of manual manipulation or fine tuning of the images could alter that impression. The mouth that had bitten into the Styrofoam had not left the marks in the cheese.

Tanguay?s dental arch was too narrow, the curve at the front much tighter than that preserved in the cheese. The composite image showed a horseshoe overlying a partial semicircle.

More striking, the person eating cheese at the Rue Berger flat had an irregular break to the right of the normal midline gap, and the adjacent tooth shot off at a thirty-degree angle, making the tooth row look like a picket fence. The cheese eater had a badly chipped central incisor, and a sharply rotated lateral.

Tanguay?s teeth were even and uninterrupted. His bite showed neither of these traits. He had not bitten that cheese. Either Tanguay had entertained a guest at Rue Berger, or the Rue Berger apartment had nothing to do with Tanguay at all.