Many times an investigation has been solved by using the strategy of "Follow the money." That' s now much more difficult because of cryptocurrencies.

A cryptocurrency is an encrypted piece of data that can only be read by someone with the "keys," which are usually kept in a digital wallet on a phone. There's a reason why these coded currencies are so popular with crooks: They are pretty much untraceable unless you have the public and private keys or specialized knowledge about the blockchain.

The most famous cryptocurrency is Bitcoin, which last year experienced a near exponential runup in value before stabilizing this year in a range of around $6,500 per coin.

A decade ago cryptocurrencies were nothing more than curiosities for computer geeks. Now they are going legitimate, but despite all of the moves toward legitimacy, cryptocurrencies remain the favored money for criminal activity online and especially on the Dark Web. They have become the financial instrument of choice for ransomware attack payments; scams; money laundering; sale of stolen, counterfeit, or illegal merchandise; human trafficking; selling of illegal drugs; sale of unlawful weapons; financing of terrorism, and many other criminal acts.

Cybersecurity subject matter expert Eric Janson recently told me, "Clearly there is a marriage between cybercrime and cryptocurrencies. Their use has and will continue to grow as cryptocurrencies, ransomware, and the Dark Web rapidly evolve."

Criminals are drawn to cryptocurrencies because they are widely thought of as being untraceable. To some extent, there is truth to that belief. But since cryptocurrencies are not issued by banks or nations, their authenticity must be determined through a complex ledger of encrypted transactions called a blockchain. A blockchain records every cryptocurrency transaction, so the transfer of cryptocurrencies can be traced by skilled digital forensics specialists.

Last year more than 400 investigators who work cybercrime, cybersecurity, and money laundering gathered in Doha, Qatar, specifically to discuss the growing popularity and use of cryptocurrencies. Their report stated that "all countries should increase training initiatives in this field."

Currently, many in American law enforcement are behind the curve when it comes to understanding cryptocurrencies, their current state, and the implications of this digital money being used in illegal transactions. "Law enforcement needs to stay abreast of all cryptocurrencies, knowing how they are being used and manipulated," says Marty Cheliak, retired Royal Canadian Mounted Police (RCMP) chief superintendent.

In his testimony before the Senate Judiciary Committee last October, U.S. Attorney General Jeff Sessions expressed his concern over the use of Bitcoin and other cryptocurrencies in criminal activity. In fact, he called Bitcoin "a big problem." He went on to mention the Dark Web marketplaces and how cryptocurrency is used in those online e-commerce sites.

There is no doubt that this is a growing problem and it impacts law enforcement at all levels. The question has been raised, is law enforcement prepared? And the answer is clearly: No.

Every law enforcement officer must stay well informed these days about the rapid and dramatic changes that are projected to accompany the multiple emerging technologies that will become mainstream in the next few years. It is now essential that organizations more rapidly respond to developments like cryptocurrencies. The criminal use of cryptocurrencies is in its early stages and growing. Its future expansion is a sure thing. That expansion brings with it the risk of cryptocurrencies being used in more and more criminal and terrorist activities.

Many believe law enforcement must rapidly come up to speed on this subject matter. Clearly, that is the major reason why Law Enforcement Learning recently announced a virtual course on the subject (that I teach). "As cryptocurrencies become the value transfer mechanism of choice for an increasing number of criminals and criminal groups, law enforcement officers must understand cryptocurrency basics and recognize when these virtual currencies are used in furtherance of fraud, theft, extortion, drug and weapons sales, and other criminal acts," says Timothy Bonadies of Law Enforcement Learning. "Our course provides officers with an essential foundation that will enable them to recognize how criminals are currently using cryptocurrencies, how these uses can be investigated, and what laws govern this rapidly evolving area."

While meaningful metrics that reasonably measure the criminal use of cryptocurrencies currently don't exist, looking at the projected growth rate of the blockchain and cryptocurrencies, we know it is significant and will grow. There have been two substantial criminal cases involving Dark Web marketplaces, one involving $4 billion in cryptocurrencies and the other $1 billion in cryptocurrencies. These clearly are indicative of a trend.

But don't think that just because the owner of a Dark Web marketplace that delivers illegal items in return for cryptocurrency is being prosecuted that the problem is solved. As fast as one criminal cryptocurrency marketplace is shut down, one or two more open up on the Dark Web and that perpetuates the value of this digital money.

Michael Coleman is a 30-year technology industry veteran with a wide range of business and government experience. His passion is working with new technologies to create solutions to the issues facing professional users.