Groves said the uniform cap was stolen from their police station lobby display case back in June. It belonged to Marshal Leonard Scherger, an officer who was killed in the line of duty in 1904 while checking on a disturbance.
"He went over there to check it out and they disarmed him and killed him with his own firearm," Groves said.
Sherger is the only Hartford officer to this date to die while serving his community.
"He's also the only unsolved homicide in this city,” Groves said.
After several months of detective work to find out who stole it, the person responsible confessed last week to throwing it in a retention pond.
"We used our wastewater treatment plant, they've got some pretty big pumps and we pumped it out," Groves said.
Nine hours and half a million gallons later, it was found soaked, but the fabric and leather are still in good shape. Groves said the massive undertaking by dozens involved pales in comparison to what the officer it belonged to paid to Hartford.
"You talk about the thin blue line, this is the thin blue line through history," Groves said.
Groves says the man who stole the cap is being charged with theft, resisting an officer, obstruction, criminal damage to property. He will also be responsible for paying for the costs to recover the hat.