By Brian Maass

ELIZABETH, Colo. (CBS4) – A CBS4 Investigation has learned that the Elbert County Sheriff’s office is missing a military M16 assault rifle and multiple agencies are involved in trying to figure out what happened to the military surplus firearm.

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Elbert County Sheriff Shayne Heap confirmed to CBS4 that the semi-automatic weapon is unaccounted for but said he could not comment further since the missing weapon is the subject of an ongoing investigation.

(credit: MCT via Getty Images)

The rifle was obtained from the federal government under its Defense Reutilization and Marketing Office program which gives surplus military goods to law enforcement. The M16 is essentially the military equivalent of the AR-15 rifle.

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Heap was not immediately able to say when the weapon went missing or where it was last seen.

He said the Elizabeth Police Department and the federal government are both assisting in the investigation.

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CBS4 Investigator Brian Maass has been with the station more than 30 years uncovering waste, fraud and corruption. Follow him on Twitter @Briancbs4.