Propane Leak Detection or Theft?

The remodel of our casa included a new propane tank and associated plumbing. None of the original plumbing was kept. After two months, I found the tank to be nearly empty! I had figured, generously, we had a six-month supply. I witnessed the initial filling watching the meter on the truck. I do not doubt that the tank was filled.

Our plumber who did the install could only find a pinpoint leak in a hose connected to the dryer.

Likely there's a broken pipe in an exterior wall or the roof, and it's venting away. Not once did my wife or I pause and say, "Do you smell propane?".

Two questions:

1) Know of anyone who has a gas sniffer that could examine the entire house?
2) Is theft a possibility? The tank is up in the mirador and fed from a high, street-level connector.

Thanks for your feedback!

I highly doubt that theft is a possibility. But, you've definitely got a leak somewhere. Extremely hard to detect if pipes are in walls or under the floor. Do you really want to dig through walls or floors to find it? Easiest is to have ALL gas pipes run on the exterior of walls or roof.
Or you were short changed on the actual delivery. You can check at the truck that the starting point is zero just like you would do at the gasoline pump. And then check on the mirador what the gauge actually reads on the tank.

I highly doubt theft too. Sounds like a leak. I would seek the opinion of a different plumber/gas guy.

They make gas detection meters - I borrowed one from a neighbor when I had a gas leak in a new construction condo done by poorly paid/unskilled laborers.. Turned out a majority of the units had gas leaks in the walls = saving money by piecing lengths of copper together, rather than buying the whole length needed. Lame-ass seals don't last. Once in the wall ~ SOL. I personally would check around the hot water heater installation for seal leaks.. ALL connector cords need to be METAL, not plastic too  - just experienced this foolishness last week myself.

Also remember that they tend to use plain old white teflon tape here to make sure the seal is tight. Propane eats that white teflon tape. I had to buy the special YELLOW one from Amazon.com but I don't know if it's available here.
When my new tank was being installed, I handed the guys the yellow tape to use. Then I stood and watched them use it.

You need to have a gas meter installed. I have one from my tank to inside my kitchen. Anytime I have gas delivered, I can actually see how much is put in the tank and at anytime I can check how much gas is in tank. May not help with present problem but will help in future. Remember full tank is usually around 80% as a fuller tank can cause explosion.

Here is a benchmark:  I have a 295 litre propane tank which is filled to 85% and refilled when it falls to 20%.  I burn through this range (65% = 192 litres) in about 4.5 months.  About 99% of the propane is used in cooking; LOTS of cooking!  My house has solar electric/water.