The U.S. Marshals Service has lost track of approximately 2,000 encrypted two-way radios and other communication devices worth millions of dollars in total, according to The Wall Street Journal. This, internal agency documents report, create what some within the agency view as a security risk for federal judges, endangered witnesses and others.

Even back when the devices were first deployed in 2011, agency leaders had difficulty tracking the equipment even after being warned about the problems by an internal technology office, according to documents obtained through Freedom of Information Act requests. Radios range from about $2,000 to $5,000 each or more. After a nationwide inventory, about 2,200 communications items were missing or accounted for. Several officials since then say that one internal count has continued to grow to more than 4,000 items.

Besides the wasted money and resources, the inventory problems raise the possibility that criminals could obtain radios and listen to them to learn details of security or law enforcement operations, the Wall Street Journal reports.

A Marshals spokesman says the agency plans to buy a new inventory-tracking system, and that many of the radios in question were older models being phased out. The agency isn’t aware of any instances where “public safety was jeopardized as a result of this,” he says in the article.

Newer radio models can be remotely disabled, the article says. The agency hasn’t done so for the vast majority of missing devices because senior managers believe most aren’t lost, but given to other law enforcement agencies or disposed of without record.