Was Socrates condemned to death by poison?

Yes - at least according to the writings of Plato he was. He managed to irritate those in charge by his criticisms of the status quo and the embarrassing questions he asked (which exposed the ignorance, corruption, and hypocrisy of the leaders of Athens) and in an effort to silence him the leaders put him on trial for and found guilty of both corrupting the minds of the youth of Athens and of impiety ("not believing in the gods of the state"). The leaders asked Socrates to propose his own punishment. He suggested a wage paid by the government and free dinners for the rest of his life instead, to finance the time he spent as Athens' benefactor since he had been working to improve Athens. The (probably irritated) leaders instead sentenced to death by drinking a mixture containing poison hemlock.