Without A Trace
Knight often raided cabins during the week as most people likely stayed away. Many cabins served as their vacation homes. If you lose something in there, it was going to be hard to remember after spending one week away from home. Knight wanted to avoid leaving anything that might indicate he was inside at some point. If he discovered spare keys, he put them in his pocket to keep them safe.
Not Stealing
He was careful to avoid any suspicions, so he was fairly shocked when this life ended for him. He then took extra measures to ensure everything he used came back to the spot where he found them. He once took a canoe in the hopes of accessing cabins across the water. After returning it to the owners, he did not simply leave it out in the open water. No, he kept it hidden behind foliage. It almost seemed like mother nature took it without any intervention, although he now know this was not the case.