Small amount of nuclear material stolen last year: Police

An instrument used to calibrate nuclear material containing a small amount of plutonium and cesium in the possession of federal experts went missing last year, according to a San Antonio police report.

According to the police report, the device and material were stolen from a rental car at a hotel in San Antonio. The story was first reported by the Center of Public Integrity.

Department of Energy confirmed that its Idaho National Laboratory employees were traveling on assignment with the radiation detection instrument and a small amount of nuclear material.

The devices "are the size of a dime and if exposed, the dose from handling these devices is less radiation than we receive in a typical day from natural sources of radiation," DOE official said in a statement to ABC News.

Plutonium and cesium are both radioactive materials that could be used in nuclear weapons.

"Efforts to recover the devices are currently under the jurisdiction of law enforcement," the statement added.

Officer Carlos Ortiz who was at the original scene in San Antonio told ABC News that the case was a typical "smash-and-grab" with no fingerprint left, surveillance recorded or witnesses available to help find the suspect.

There have been no additional reports related to the incident since.

Federal watchdogs have previously flagged troubles tracking lost nuclear material overseas. Last year, the U.S. Government Accountability Office has published a report calling for improved nuclear security reporting specifically by the Energy Department.