CHESTERFIELD, Mo– Police here are warning the public not to use the blue drop boxes in front of a busy post office, as law enforcement and postal service investigators work to solve a string of mail thefts in the St. Louis region.

Chesterfield police have worked on at least 26 reports of mail theft since the start of July and on Monday reminded people to only conduct their business at the Swingley Road location while inside.

Clayton Police made a similar recommendation in April. A Chesterfield Police spokesman declined to say how the boxes were breached by thieves, citing an ongoing investigation with postal service inspectors.

A message seeking comment was not returned by postal service representatives.