[media-credit name=’TAYLOR HUGHES/Herald illustration’ align=’alignright’ width=’336′][/media-credit]Late-night mischief has Platteville police looking to catch street sign thieves purple-handed.

For years, an average of five to six "named" street signs have gone missing around the University of Wisconsin-Platteville campus each week. But the problem has gotten more serious recently, as the focus has shifted away from street signs to stop signs.

Platteville police say twelve stop signs have gone missing since school started last month.

The missing stop signs have caused fatal accidents in the past, and Platteville residents are worried that serious wrecks will now happen again in the near future.

"When you take a stop sign out of there, it's only a matter of time before someone misses an intersection," Platteville Police Sgt. Terry Terpstra said in a release.

And Platteville police and residents are both placing the blame on college students.

"We haven't experienced the problem over the summer when school is out of session," Lt. Bruce Buchholtz of the Platteville Police Department said. "It's safe to assume through anecdotal evidence that the college students are removing the signs."

Police have not given up hope in finding the thieves. As a new security feature, they have started putting invisible gel on the edges of the signs. When the gel mixes with the oils of the hands it turns purple, making it easy to catch a criminal "purple-handed."

"The affects of the gel are similar to that of a permanent marker," Buchholtz said. "You have to really scrub to get it off, and in most cases it takes days."

He added that the gel has the ability to seep through gloves.

Though the number of campus police has not grown in the past couple years, lack of surveillance is not to blame for the thefts.

"I don't think we should be paying police officers to baby-sit the signs," Buchholtz said. "People should have respect for other people's property and respect for the lives that could be lost."

According to Officer Dale Burke of the UW-Madison Police Department, sign theft is no longer a major problem around the UW campus, though Randall Avenue signs were a popular target in past years.

"Sign theft hasn't been a problem in the last couple of years," Burke said. "That can be credited to the fact that we have patrolling officers at every time of the night."