NOBODY LEAVE THE ROOM!

We had to solve this puzzle for my philosophy class this week. I don't know whether or not my professor came up with this, but I figure it's unlikely, so I'm not sure who to give credit to. Anyway, see if you can figure it out. It took me a piece of scratch paper and about 10 minutes.

NOBODY LEAVE THE ROOM!
Smith has been found dead in the bar, his drink poisoned.
Four men, seated on a sofa and two armchairs in front of the
fireplace (as shown above), are discussing the foul deed. Their
names are Lee, Jones, Garcia, and Green. They are, not necessarily
respectively, a mechanic, a restaurateur, a teacher, and a doctor.
1 . The waiter pours a second glass of whiskey for Garcia and a
second beer for Jones.
2. The mechanic looks up and, in the mirror over the fireplace, sees
the door close as the waiter leaves the room. He then turns to speak
to Green, next to him.
3. Neither Lee nor Jones has ever been married
4. The restaurateur is a teetotaler.
5. Lee, who is sitting in one-of the armchairs, is the teacher's
brother-in-law. The restaurateur is next to Lee on Lee's left.
Suddenly, a hand steals forward to put something in Garcia's
whiskey as it sits on the table. It is the murderer. No one has left his
seat, no one else is in the room, and Garcia is not suicidal.
Who is the murderer? What is the profession of each man, and where
is he sitting?

Hints: It's not the waiter.
Only someone sitting in the sofa can see the waiter through the mirror.
A teetotaler is someone who doesn't drink alcohol.

Highlight below with your mouse below to see the answer:
Lee, the doctor, is in the armchair on the left of the picture.
Green, the restaurateur, is to Lee's left on the sofa.
Jones, the mechanic and murderer, in also on the sofa.
Garcia, the teacher is in the other armchair.