DELPHI, Ind. -- Indiana State Police will release a composite sketch of the suspect of the murders of Abigail Williams and Libby German on Monday, Call 6 Investigates has learned.

According to multiple sources, the new evidence may help the public identify the man on the bridge, who police call the prime suspect.

Williams and German went missing about five months ago, while on a hike along the Monon High Bridge in Delphi, Indiana. After they didn’t return to be picked up by family members, police searched through the night for 14-year-old Libby and 13-year-old Abby.

The next day, their bodies were found.

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There has been no arrest, but investigators are optimistic the release of this new information will bring them closer to their motto, "Today is the Day."

In response to the new evidence being released, Mike Patty, Libby's grandfather, said, "Please spread the information."

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In the five months since that day, Indiana State Police, the FBI and multiple other agencies across the state have spent countless hours investigating and interviewing witnesses and possible suspects.

Indiana State Police Sgt. Kim Riley said investigators have received over 18,000 tips and interviewed over 1,000 potential suspects. More than 20 people have been arrested on unrelated charges because of the case, but so far no one has been charged with Libby and Abby's murders.

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The reward for information leading to the arrest of their killer has grown to over $230,000 since February, but so far that hasn't led to any arrests.

Call 6 Investigates’ Paris Lewbel and Rafael Sanchez are speaking to their sources and working on this developing story.

Check back to this page for updates.

Indiana State Police released a picture of a suspect, which was taken by Liberty on her cell phone. She also captured a man's voice saying "down the hill" during what police call "criminal activity." You can listen to that recording and see the photo below.

Indiana State Police ask anyone who recognizes the man or the voice, or who may have any other information, to call the Tip Line at (844) 459-5786 or 1-800-225-5324 (800-Call FBI). Tips can also be emailed to Abbyandlibbytip@cacoshrf.com. Information can be reported anonymously.