Complex sentence: Police had found no exact match between DNA found at the crime scenes and any of the profiles in California's DNA profile database, so they searched the database for stored profiles that demonstrated sufficient similarity to allow police to infer a familial relationship.
Split into simpler sentences: Police had found no exact match between DNA found at the crime scenes and any of the profiles in California's DNA profile database. So they searched the database for stored profiles that demonstrated sufficient similarity to allow police to infer a familial relationship.