Gold dust worth 700,000 dollars (£437,000) has gone missing from a medical research lab in St Louis County, and police are trying to determine if it was lost or stolen.

Police in Chesterfield, which is about 20 miles west of St Louis, began an investigation this week after a Pfizer employee conducting inventory could not find the gold dust purchased last year for use in research, the St Louis Post-Dispatch reported.

Police captain Steven Lewis said no one is "sure if they just didn't account for it and it was used naturally, or if it was stolen or misplaced". Pfizer said in a statement it is working with law enforcement and takes the matter seriously. It was not clear what purpose the gold dust has in Pfizer's research.

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