I always reckoned that there were small, but noticeable increases in the incidence of armed robberies that coincided with periods of block leave from Germany. Up until the mid-90s you could walk into a bank or building society and 'withdraw' between 10 - 20K in two or three minutes. That makes for a memorable summer leave.I know an armed robber who subsequently joined the army as an officer.
The security technology and forensics were very basic. If you didn't boast about it afterwards, your chances of being caught were almost nil. It was essentially the perfect crime, you didn't have to function in a criminal milieu and your overall exposure to arrest could be limited to less than 10 minutes. You'd have to be really unlucky or stupid to get caught.
Quite a few members of HMF were at it, and not just mad squaddies.