Dr. George Wenzel and his colleague Dr. Martin Hupp are two expert biochemists researching brain-wave-changing drugs. Their work has long been regarded as being worthy of the Nobel Prize, in particular since their recent success with large cats. They showed that they could boost the intelligence of those animals to near-human level. The main challenge they had to overcome was the side-effects on the cats. Being so intelligent made them extraordinarily aggressive. (Maybe they realized their situation in full?)
Anyway, the doctors' latest discovery was generally assumed to be so fundamental, that there wouldn't be a choice but award them the prestigious prize.
So it came as a shock that on the very day a press-conference was announced which would disclose their latest results, Dr. Wenzel was found dead in the animal laboratory. He was ripped to pieces by one of the tigers they were experimenting on. His colleague Dr. Hupp could not explain at all how Dr.Wenzel could have been so careless.
"He normally took all precautions very, very seriously," he said. "And this time it was especially tragic. We had just discovered the proper drug to get all the positive effects and keep the animals calm. I tested it myself, and I've left George all the notes - see there on the table. I really don't understand this. The formulae does work properly. I have even cross-checked it this morning. The only explanation I can possibly think of is that he tried to modify the mixture even a bit more... But why would he do that?"
Inspector Edo Clu, who is leading the investigation, is wondering the same thing. However, it does not take him long to have Dr. Hupp as his prime suspect. Who else would have more profit of the untimely end of Dr. Wenzel than him? The Nobel Prize, after all, can only go to living scientists.
So he gives the surroundings another very close look, then calls Dr. Wenzel's mother to ask her a single question, and based on the answer arrests Dr. Hupp on suspicion of murder.
The puzzle is: What did inspector Edo Clu ask Mrs. Wenzel and what was the answer?
Now the two relevant photos from the crime-scene are shown below. (please use your imagination a bit, I'm not an artist) One shows the desk of Dr. Wenzel on which a note from Dr. Hupp is found together with a couple of post-it blocks and some pencils which have been used all over the lab.
The second shows a group of labelled bottles all standing in a group (no sorting) on the shelf. According to Dr. Hupp, these contain the latest drugs. The bottles are labelled with the post-its and pencils found on the desk (as are other items in the lab on different photos not shown.) There are two distinct handwritings on them.
Transcription of the letter:
George, we did it! Yesterday's experiment series went perfectly fine. None of the animals showed any of the side-effects at all! It seems that you were right about adding the Xonophoricum Hauratio to the mixture. It totally neutralized all of the aggression while keeping the brain-stimulating effects. You have to see this for yourself, and then you should prepare for the call from Sweden! Have you ever cuddled with a tiger? Now you can. He actually purred while I stroked him yesterday. Unbelievable. I have left one of the bottles in the prep-room, if you want to see for yourself. As it was a long day, and tomorrow will be even longer with the press interviews and stuff, I’ve gone home already. See you tomorrow. Make sure you come shaved, our pictures will go around the world!
and the five bottles:
Series VII/3/2.1; What do you think,George?; no good
Series VII/5/1; extra aggressive!
Series VII/5/1.1; placebo
Series VII/6/1; new mixture;brain-boost! This is it!; too aggressive; Don’t use!
Series VII/6/1.0; +XoHa
This is my first 'crime' puzzle and I'm sure it could be better, but I hope it's still good fun. Asking questions in the comments is welcomed and may lead to edits. If there is no solution in a week (which I highly doubt), then I will start giving explicit hints.