The police find a hotel key on the second victim, which leads them to one of the mobsters.
When she pulled back she showed him something in her hand, a hotel key with a bright orange tag.
He handed me a key, explaining it was his hotel key.
That is, Trenkler planned to return all his hotel keys except this one.
"Returning a hotel key is a simple matter," explained Cranston.
Gaudry forgot himself and brought the wrong hotel key here.
He spotted a hotel key in her briefcase just as she was snapping it shut.
She gave this to Cranston and said, "Sometimes a hotel key will work on other doors."
He dug his hotel key out of his pocket.
"I'm your husband," he said, and reaching in his pocket, he displayed a hotel key to my room.