When the behaviorist was called in and the family started working with Murphy, was it actually working? Was Murphy's behavior getting better?

You said the family eventually gave up on it because it was too much work and then they had a baby and everything kind of went down hill from there.

If the family were to adopt him out to the boss and he was to stay at his place of work, would a behaviorist be called back in? If everybody at this place of work was in agreement to all try to work with Murphy and they brought a behaviorist in, I don't see why Murphy couldn't stay at work. It would be a great experience for the workers - a bonding of sorts. But it sounds like he might be alone for long periods of time. Am I correct in saying that? If that's the case, I don't think that would help his behavior.

This sounds like a case for the Dog Whisperer.

It's a shame they would have to put him to sleep. Springer Spaniel's make good hunting dogs. Maybe a hunter would want to adopt him if it is spelled out that he has aggression issues and needs serious training.

I don't know. This is so sad. At the same time you don't want Murphy seriously injuring a human or a dog or cat.

Good luck.