By Daniel Kelley

(Reuters) - A photo of a police officer in Camden, New Jersey, apparently asleep in his cruiser has prompted an investigation in the U.S. city with the nation's highest violent crime rate in 2012.

The photo, which shows the uniformed officer wearing sunglasses, head cocked back and mouth agape in the driver's seat, began circulating on Camden-related Facebook pages this week.

It was unclear whether the officer was napping or caught yawning at a bad moment, whether he was on break or on duty, or how long he had been on patrol.

"It's under investigation," Michael Daniels, spokesman for the Camden County Police Department, said on Friday. He declined to identify the officer.

Camden has scrapped its city police force as a cost-saving measure, and the county force replaced it in May.

CQ Press, which tabulates crime data, ranked Camden, a city of 77,000 people across the Delaware River from Philadelphia, as the U.S. city with the highest violent crime rate in 2012.

The county police department said it has already reduced crime, citing a 91 percent drop in daytime homicides - down to one from 11 in the same period last year.

But Camden's safer streets come at a cost to county officers, who work 12-hour overnight shifts, said Tracey Hall, a retired Camden city police officer who has criticized the county department's working conditions.

"Coming in at midnight when it's dark, and working into the afternoon, it's hard on the officer's body," Hall said. "We go from zero to 60 every other call. Eight hours in Camden is like working 16 hours anywhere else."

(Editing by Barbara Goldberg and Xavier Briand)

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