German Shepherd Police Dog-3 years old

Question
My sister and her husband work for the local prison.  The husband knows a gentleman on the K-9 unit whom has a 3 year old male German shepherd.  The dog has been in training with them for some time now and has went through the process up to the attacking part.  My sister explained it as when they want him to attack he won't, he just wants to play.  So they are getting rid of it.  They want to give it to someone but if they can't they will put it down.  I'm 26, I have had German shepherds exclusively (but females).  Only 2, but they are my favorite dog and I would never want any other.  I feel is a great opportunity to get the dog for free, trained, house broken and with all shots.  I work during the day, but come home for lunch and am home by 5 nearly everyday.  My biggest concern is how will this dog transition to becoming a family dog?  Should I worry that it will be too aggressive when visitors come to the house?  I have yet to meet the dog but am not making any final decision until I do.  Can you speak, from experience, on a situation similar to this?  Transition? Aggressiveness?  Thanks for your time.

Answer
The dog is presently three years old; I have no idea how long the police have had him, what training he has undergone (and how experienced the trainer is!) or whether or not he resides in an officer's home or is presently (and always has been) a kennel dog. These are important facts I need to know in order to help you evaluate whether or not the dog is suitable for your home.  Also, is the police department making you sign a contract indemnifying them should the dog show (or offer) aggression toward humans?  Are you being asked to hold them "blameless" should this dog attack someone?  At age 26, you are a very young woman.  Life holds much in store for you, trust me.  At some point in the future, you may want children; you may marry or take a life partner; you must consider these points when making this decision.  MANY former police and military dogs are in normal households in the US;  I've met more than my share, and they are all stable dogs.  But this stability is determined by how the dog was contained, how it was socialized, the training it has received, etc., as well as inherited temperament.  It sounds to me as if this dog is not a candidate for aggression problems but before I answer your question I need you to do your homework: get the answers to the questions I've asked you, and repost.