How was Lyons killed?

Hint 1 of 5:

Several people said that he was poisoned.

Hint 2 of 5:

With a rare poison, at that.

Hint 3 of 5:

Porky Shinwell gave you some important clues about the murderer.

Hint 4 of 5:

O'Neill met with Derrick Quinn just before Lyons was killed.

Hint 5 of 5:

And Derrick Quinn sells rare snake venoms.