Cops scale back manpower in unsolved Indiana double murder but stress they are 'not giving up'

— -- Authorities searching for the killer of two Indiana teen girls are "scaling back" manpower in the over month-long investigation, but stress that they aren't giving up and the case isn't going cold.

Each day there have been as many as 40 to 50 officers, and sometimes up to 100 officers, working to solve the double murder of Abby Williams, 13, and Libby German, 14, in the more than five weeks since the teens were found dead, said Sgt. Kim Riley of Indiana State Police.

But now, the number of officers working each day will drop to about 20 to 30, Riley told ABC News.

Police explained that the steady stream of tips coming in has become more manageable. For the most part, tips have slowed down recently to about 100 to 125 per day, Riley said, which has allowed police to get caught up.

Now, the Delphi police and the Indiana State Police's Lafayette office are aiming to have not as many outside agencies helping day to day, Riley said.

The FBI is pulling out some of its resources, Riley said, and some state police officers who came from outside the Lafayette area will return to their own communities. Riley said the operation to scale back has been going on for the past week or week and a half.

While police have received a total of about 15,000 to 16,000 tips, no arrests have been made since the girls' murders shook the rural small town of Delphi, Indiana, in February. The eighth-graders disappeared Feb. 13 while on a hiking trail near their hometown and their bodies were found nearby the next day.

As police hunt for the killer, the only clues that have been released to the public are this photo of a man who police say is the prime suspect in the investigation and a chilling recording found on Libby's phone with just three audible words: "down the hill."

While Riley said they are "scaling back" manpower, he stressed that authorities are "not giving up" on the case.

“It doesn’t take as many officers to do the work,” Riley said. "We are not giving up on this case whatsoever, it’s just that we are utilizing manpower a little bit better than we had before."

Riley added, "We're still committed to this. Just because we’re scaling back doesn’t mean we're not committed to finding the perpetrator."

State police explained in a statement today that "investigators who may return to their 'home base' will still be within a phone call’s reach and could potentially return to this assignment. ... Those investigators are simply returning to their respective areas to follow up on investigations which have been temporarily delayed" since the Delphi case began.

State police stressed that "this does not mean the investigation is going 'cold.' To the contrary, each investigator remains strongly committed to reaching resolution."

Carroll County Sheriff Tobe Leazenby agreed, telling ABC News today the case is not going cold.

Leazenby said in a statement, "We stress this investigation is ongoing and is not without resolve as we will find those responsible and reach proper closure for Abby and Libby and their families.”

State Police Superintendent Doug Carter said in a statement, "We remain committed to this investigation and the Carroll County and Delphi community until 'this evil' is eradicated."

People can provide information by calling the tip line at (844) 459-5786. Information can be reported anonymously. Tips can also be emailed to abbyandlibbytip@cacoshrf.com.