Sandpond is seen when Moonpaw, who was banished for killing three cats, returns to SparkleClan and calls for a clan meeting. She tells her former clanmates that the cats were not killed by her. Sandpond responds by asking her who killed them if she didn't.
Much later, it is revealed that everything from Snowsong framing Moonpaw for killing the cats, to him becoming leader of DarknessClan was a dream. Moonpaw wakes up to find every cat in SparkleClan dead, which presumably includes Sandpond.