I agree... He has been determined to be normal and law-abiding. 

No one knows his motives. The police are asking the public for help because they have run out of people to ask. 

Even the hotel room setup seems inconsistent with a mass killer. Why would he need so many guns? Unless he was going to sell them? 

If he was going to kill himself then why write such an odd suicide note of elevations and angles? And was the note even written at the same time of the killing? Or did it just happen to be there? Could it have been forged? 

Preparation of the room is estimated to have taken days for one man. Why go through all that trouble? Or could a team of two or three people accomplish the same thing within hours?