Mafia 84. Memorized it, turned it in, forgot it!

I'm home, read the newspaper again, and yes, you're right about Ment, it seems he's either a class president or a nerd :(

I looked at the profiles, I agree.
The cookbook is a direct clue to the murderer, and the cognac and refrigerator are just for fun, I think. If we judge very straightforwardly, then it's Olam Havel, who forced Ment into the army with his jelly-like hand :)

There are also these options from Google:

Several chefs named Alex. Any choice :)
Hexane is used in the extraction of vegetable oils and as an organic solvent.