Unlike in popular fiction, private eyes are not generally involved in solving murders. Most of the 1500 detective agencies in Germany, for example, work for big business. This is an industry worth around 220 million euros a year - most of it spent on surveillance hardware and specially planted employees. The demand stems chiefly from fear of commercial espionage or theft. Legal restrictions on secret video surveillance - permitted only in cases of concrete suspicion - mean that investigators often find themselves in legal limbo. Up-market agencies are dissociating themselves from the black sheep in their midst. Claudia Laszczak met some of these modern-day Sherlock Holmeses in Berlin. --------------------------------------------------------------------- Private detective Ralf Behm packs his case full of gadgets before setting out on his new assignment. His job is to tail a company employee who is supposed to be on a business trip - but whom his boss suspects is in fact taking a vacation. Ralf Behm gets on the case and secretly shadows the employee. Jörg Behm: "Proving something against people who think they're safe only works when you're hiding in your car. Then you're able to observe them doing something they're not supposed to." Reporter: "And you're allowed to do that?"Jörg Behm: "Yes." German law allows companies to conduct private investigations. But detectives have to watch out for themselves as well. Jörg Behm: "We have to check whether the person in question really is their employee. There are certain clues that we generally check beforehand. If confirmed, we follow up and try to either substantiate the information or rule out the issue." Tracking an employee is only permitted where a concrete suspicion exists. Detectives frequently serve as substitute police for the corporate world. A lot of managers prefer to resolve problems out of the public eye. Moonlighting, fraud and theft - there is plenty of work for private investigators. They are allowed to gather personal information about staff - but spying is not permitted. Data protection experts watch the work of Germany's 15 hundred private eyes with unease. Peter Schaar is the Federal Commissioner for Data Protection. He says: "Clandestine tracking, surveillance or spying must only be allowed under very exceptional circumstances, where there is a concrete suspicion of a contractual violation or criminal offence." Video surveillance is likewise allowed - albeit for a limited period of time - where employees are suspected of theft. Ralf Beyer is a detective and an expert in special camera technology. He installs miniature cameras in supermarkets and stores. Ralf Beyer says: "Three quarters of all investigative assignments involve surveillance cameras like this." The tiny devices can be well hidden - like this one - tucked into a smoke detector. Surveillance is more common than employees may think. Ralf Beyer: "From classic theft incidents to acts of sabotage in major companies. Resolving issues like not working the full hours, or truancy at the workplace. The classic sick-note scenario is likewise still a major issue for in-house investigations." Modern technology has added a new dimension to private surveillance. Satellite detection via GPS is also used by detectives. A transmitter - attached to the car and out of view - provides details about where someone is going or where they currently are. So much for anyone dreaming of another holiday with the company car.