When Wilkes is showing his torture room to Murphy and Tutuola, he holds up a cast cutting saw and says "Want some skin in the game?..." then activates the saw.
A cast cutting saw is specifically designed NOT to cut skin. It would be utterly useless to Wilkes.
A cast cutting saw looks scary but it can't be used to hurt someone. It doesn't even hurt if placed directly on the skin. It just tickles a bit.
During the line up, everyone must have a similar appearance., the suspect was the only one wearing glasses.