One thing I'd advise CSI to look at would be drug and toxin residue. I have lots of reasons for saying that, but if they found (for example) any residue of an illegal drug (say, meth...) in the cars, they would really want to do a kind of archaeological look at the house. It's possible to collect residues in bathrooms, flooring, curtains, etc, so as to give a good chemical picture of drugs used in the house within the last 6 months to year. Plus, the actual hiding of drugs in the house can be complicated. So...I wonder about drugs.
People who hide drugs (let's say that TS or AS wanted to hide their use from the other - as users often do) can be very clever about where they hide them. This is a part of a crime scene that most LE would want to investigate. People who hide drugs, well, they are good at acquiring and hiding toxins, let's just say that.
Stuff may have been flushed as well - not just drugs, but other evidence. Some of it may still be there, as it takes a while for somethings to get all the way out to the sewer main - and even then, the main pipe can be forensically examined.
