BURLINGTON, Iowa (AP) — Workers at the Des Moines County Courthouse are sniffing around the 77-year-old building and using blueprints to find the source of a mystery smell.

The sewer-like stench has been wafting around the basement and parts of the third floor, including the jury deliberation room, the Hawk Eye reported . The unpleasant smell has been noticeable over the past few weeks, though workers say it happens every fall.

"You've probably noticed we're still chasing the smelly gremlin here in the courthouse," said Rodney Bliesener, the county's maintenance supervisor. "We're still trying to find it."

Courthouse employees have tracked past odors to suspect pipes and busted holes in the building's walls to seal cracks. Maintenance workers bored through marble and brick in the women's restroom to patch a pipe that was creating a smell last year.

Panels also line many walls in the courthouse where workers created holes to fix pipes.

Maintenance workers suspect that a pipe connecting the basement to the jury room might be creating the current smell. They plan to open the wall after jury trials end this week.

Bliesener believes changes in the air pressure might be pushing stinky air out into the courthouse, though he isn't positive.

Workers have found a temporary solution: Running the boilers in the courthouse's sub-basement seems to make the smell vanish.

"It's like a smelly ghost," Bliesener said. "It just pops in and out."

Bliesener said he's confident workers will identify the source.

___

Information from: The Hawk Eye, http://www.thehawkeye.com