DELPHI, Ind. (WRTV/ABC News) -- Police investigating the unsolved murders of two northern Indiana teenage girls are hoping the crime's anniversary spurs a wave of tips from the public that can lead them to the killer.

Carroll County Sheriff Tobe Leazenby says State Police and the FBI have increased staffing to field an anticipated increase in tips about the murders of 14-year-old Liberty German and 13-year-old Abigail Williams.

The girls vanished last Feb. 13 while hiking near their hometown of Delphi, about 60 miles northwest of Indianapolis. Their bodies were found the next day.

At a news conference Tuesday afternoon, Indiana State Police Superintendent Doug Carter said we can not allow evil to prevail in Indiana.  Carter added this case is personal to him because those two girls were "everyone's daughter."

Click here to visit the Indiana State Police website with details of the investigation, a sketch and photo of the suspect, and audio clips of the suspect, 

If you have any information in this case, please call the tipline at (844) 459-5786.

Sketch and possible photo of the suspect