In gracious language, the note expressed his regret that he would not have a slot open in his laboratory until next May.
Might have been next millenium! Shitty luck. No chance to observe my suspect at close range. Why? Because he was rightfully suspicious of me. No use trying to appeal his decision. That would just make matters worse. Hopefully he wasn't already destroying evidence and covering his tracks.
What to do now? Old Man Westley would probably say, "Muddle on through as best you can."