"During the time you studied there, had you free access to the office at all hours?"
"I had."
"I judge, then, that you must have possessed a pass key?"
"I did."
"Is that key still in your possession?"
"No."
"How did you dispose of that key?"
"I think it was lost; it has been out of my possession for some time."
"Where did you lose this key?"
"I do not remember; possibly at home, possibly at the office. It has been out of my possession for some time."