I'm not a detective and I'm not going to spend time trying to justify whether they should qualify or not.

Hire a leak detection specialist.

If you wanted to steal your customer's money, you'd take little bits at a time so you could theoretically do it for a long time without detection. 

Know how to turn off your water, gas and electric service; and keep the necessary tools in your vehicle.Know how to do basic roofing: shingles, 2 part roll roofing, flashing and tar.Know how to replace an electric breaker, light switch and outlet.Have a RUP license (Restricted Use Pesticide).Know how to do basic welding (Stick, MIG or gas; no need for TIG).Have a box type animal trap, and know what to do with a trapped feral or wild animal that is a problem.Know how to do common repairs to major appliances (broken air circulating fan in a fridge, thermal fuses in a dryer, agitator dogs and transmission coupling in a washer, blower motors & capacitors in central heat/air, gas thermocouples in water heaters and space heaters, know how to clean a pilot light orifice, etc).Know how to do concrete and asphalt work.Know how to do small engine repair (mowers, chainsaws, weedeaters).Know how to detect and remedy gas and water leaks.

It will cost me $35 to have a local detective agency skip trace them for their new address.  

So the answers are:- Some times the buyer, sometimes the seller who picks the title company- And it is OK / safe to use the seller's tittle company (I'm a buyer)- Code violations can be detected by home inspectors. 

Costs you 50 cents if they have a new one.Otherwise a private detective or Google, whitepages.com or pipl.com etc. may find it after a few months.Also, you can sue without their address, possibly.

We are calling mobile numbers which are better at detecting robo callers I think.  

@Ivy HaileyShoot me an email I wrote an article on detecting fraud.Paul

That takes some detective work on your part or literally pay a private detective to track down the heirs.