Question: A law firm I've been in contact with has recently been broken into 3 times in the past 4 months. In spite of a number of laptops and other equipment containing sensitive information being stolen, the tech support company occasionally doing work for them has done nothing to safeguard against future theft. I proposed installing anti-theft software (such as Prey) and later considered establishing one system as an information-gathering honeypot with hidden keyloggers sending information to a number of email addresses. 

All physical security best practices aside, what other measures could possibly be implemented here? These are all Windows systems. I don't doubt the separate incidents are linked and being carried out by connected if not the same criminals. 

The firm has already been in contact with the local authorities. However due to a lack of documentation on the stolen items, there are no serial numbers or additional helpful information on the missing devices besides make and model, so recovery seems a dead end but at the least they're aware of the incidents.

Answer: 
Apart from using tracking software and full disk encryption, the company may invest in educating the concerned people to use their laptops only to connect to virtual private servers ([VPS](https://en.wikipedia.org/wiki/Virtual_private_server)) where they must save their data. That way, if a laptop of a given worker is stolen, no data could be found within it (I take in account the fact you stated good safety practices are known). A similar goal can be achieved if they can invest to buy their own -physical- servers.
You can consider modern solutions like UEM (Unified Endpoint Management) solutions. It comes with a whole range of features to manage Windows devices (mobile and PCs) along with other platforms. In your situation, you can always use the remote tracking option or if you are also concerned about the data, you can remotely wipe them too. And also, when you enroll a device in UEM, it automatically captures its details which once exported can also be treated as an inventory of all devices you are managing.