Suppose you have a conjured (or bound) spirit that is given some order that makes sense whether or not the summoner is alive, ex, "attack (that person)."

If the summoner dies, what happens to it? I think the answer is that its services are terminated prematurely and it's free to leave, but I couldn't find anything explicitly saying anything about this. This FAQ entry suggests it but I can't find anything else.

Q:Is there a maximum period of time a spirit power may be used continuously at the cost of a single service?

A: Unbound spirits will only perform this service until the next sunrise or sunset, at which time it will depart, no matter how many services it has remaining. Bound spirits will continue to use their power continuously [b]while the magician is alive[\b], until disrupted, or until the magician orders them to use another service. A spirit subject to long-term binding (p.94, Street Magic) will continue for a year and a day, whether the magician dies or not.

Please tell me where in the books this is addressed.

I don't know if its in the rules or not, but for unbound spirits I simply have them disappear. Their summoners is dead and thus they're released from servitude. For bound spirits, I check to see if they go free as per the ally spirit rules.

This is a thread on this from two weeks back. Most was handled there.

Also, see the Spirit Services subchapter on page 186 of SR4a, plus page 94 of Street Magic.