[quote=@Caits]
Simple observtion. 

he didn't kill the magazine people. 

He could have damaged the guild. 

Could have killed Sasha and Lazarus before, but didn't. 

So, conclusion: He's not behind the poisoning. 
[/quote]

True, but he could of also knew that Sasha already had the cure for the poison so Lazarus would of still lived. 

Just freak her out.

And find out Prince was a medical expert by looking into Dragon Fang since he's been there for about 4 years. And he's seen him go with Sasha just before the train station.

But I see your point xD