Brothers Jim and Mike Marshall owned and operated a jewelry exchange aptly named J&M Precious Jewel Exchange which had been left to them in their Father's Will. Although their large inventory consisted of various precious stones from all over the world, diamonds were the mainstay and specialty of the business. Due to the high values placed on their inventory, certain security precautions had been implemented by one of the leading security companies to prevent thefts.

The security system was very high tech and designed to thwart any robbery attempts. It had been specially designed for the Exchange and the habits of the two brothers. Jim had always been very bad at misplacing his keys and Mike was extremely forgetful when it came to remembering security codes. Therefore, the security company had installed a system that was activated when either Jim or Mike placed their right hand on the entry pad thus eliminating the need for keys or security codes. All was well until..............

One morning Jim arrived at work and discovered that they had been robbed sometime in the night. The alarm had not been disarmed and had not gone off. There were no visible signs of forced entry. Everything was as he had left it the night before when he set the alarm and left - except that the inventory had been almost completely wiped out. He immediately called the authorities and then called his brother, who was out of the country on a short vacation for the last week.

Detective Jones received a call to respond to a robbery at the Exchange and arrived a short time later. Detective Jones routinely put on a pair of standard issue police latex gloves and, upon entering the building, proceeded to examine the doors and other possible points of entry. He found there to be no signs of forced entry. Although, upon a close inspection of the security pad, he found that the tip of his gloved finger seemed to stick to the outer edge of the security entry pad. Once inside, he found no indication that the premises had been searched in any way, as a normal robbery would leave the premises in a state of disarray. Therefore, Detective Jones requested Jim call and assemble all of the current employees of the Exchange. At the current time, there were only three employees. Robyn Moore, a young and attractive woman, who was the receptionist/secretary and had been with the Exchange for over five years. Jim stated that she was very trustworthy and loyal. John Banks, who validated the authenticity and quality of the various gems and diamonds, and had been with the Exchange for over twenty years and had become a part of the family as he had also worked for Jim and Mike's father. He had heavily invested in the Exchange when the two brothers took control and was somewhat of a "silent partner" which was unknown to the other two employees. The third employee, Bill Copeland, had recently been hired to assist John in the validation of the quality of the various gems and diamonds.

Once all of the employees were present, Detective Jones interviewed each one as to their whereabouts on the previous night. Robyn stated that she had joined her parents for dinner and, due the late hour, had stayed the night with them. John indicated that he and his wife had gone to dinner with 2 other couples and then they had all gotten together for a night of bridge. Bill replied that he had an early dinner, and retired early as he had been feeling a bit under the weather. He further stated that he had watched a Twilight Zone marathon on television until he fell asleep.

Detective Jones asked them to please be patient as he needed to have another look around the premises. First he thoroughly inspected the desk and surrounding area where Robyn spent her day. Nothing was amiss. He then proceeded to inspect the office and work bench where John worked with the various stones and diamonds. He noted a box of thin latex gloves which were used when inspecting the stones and diamonds. Again, he found nothing amiss. Lastly, he inspected the office and work area occupied by Bill and noted a box of latex gloves and a box of self adhering 8" by 10" transparent sheets, which are normally used to protect important documents. The box had been partially used and there were several discarded sheets in the waste basket. Upon completing his inspection, he advised Robyn and John that they were free to leave and thanked them for their time. He then proceeded to arrest Bill as the thief.

How did Detective Jones decide that Bill was the guilty party and what evidence led him to that conclusion?