According to Susanne Kufeld, a corporate security administrator for the company, several hundred kilometres of track in North Rhine-Westphalia and eastern Germany have already been marked with the substance.
The substance leaves markings on thieves' hands and clothing that can be seen under ultraviolet light, making it easier for police to identify them when caught. It also makes metal more difficult to sell because it's easy for buyers to determine if it's stolen.
“It makes it easier for us to recognise tools, offenders and stolen heavy metals,” said Jörg Schulz, head of the Federal Police's Leipzig division.
As commodity prices have surged in recent years, metal thieves have become more brazen, causing Deutsche Bahn a loss of €10 million in 2010 alone.
In first nine months of this year, thefts in eastern areas such as Saxony-Anhalt and Thuringia more than doubled compared to the same time period last year. Nationwide, thefts have doubled, according to the Bahn.
Although Deutsche Bahn only started the DNA marking this year, the substance has already become a relatively way common way for government and property owners to protect their things from thieves. Frankfurt (Oder) near Germany's border with Poland is running a pilot programme, providing the DNA to auto owners to mark their property.
In some countries there have already been convictions. In Britain, a 24-year-old was sentenced to 22 weeks in prison earlier this month for stealing lead from a market after the metal was identified as having artificial DNA markings under ultraviolet light.