Investigators have released an audio clip recorded by murder victim Libby German, believed to be the the prime suspect saying "Down the hill."

FIVE months after the murder of two Indiana teenagers, police have warned armchair sleuths to “stop posting your dubious detective work on Facebook”.

They say armchair sleuthing prompted by the release of a composite picture of a suspect is hindering the long-running murder investigation of Delphi teens Abby Williams and Libby German in February.

The FBI composite sketch of a man suspected in the February killings was released last week, to help “clarify” pictures previously released in relation to the mysterious “man on the bridge”.

The artist’s sketch is based off witness tips, including one woman who told police she saw this man near the Delphi Historic Trails the day Abby and Libby were murdered.

Release of the sketch resulted in a surge of tips. But sadly, it also resulted in a surge of fresh social media speculation.

Carroll County Sheriff Tobe Leazenby told Fox 59 News investigators received more than 1000 leads via email and telephone within 24 hours of the release of the sketch of the man.

Before the sketch was released, police said tips had decreased to about 10 per day. “The public is looking at this again … it’s helping. It’s also encouraging for the investigators, too,” said Indiana State Police’s Sgt. Kim Riley.

But two days after the sketch was released, police had to appeal for armchair sleuths to stop posting their amateur detective conclusions on Facebook, after a number of posts in which Facebook users combed websites to find mugshots of random men who resemble the composite sketch, then post them alongside it.

Indiana State Police chief public information officer, Captain Dave Bursten, said the growing problem of “armchair sleuthing” was hindering the investigation, according to the Indy Star.

“Those (pictures and posts) are of no value and take up investigative time,” he said.

He also warned “a person that does that may open themselves up to some civil liability”.

“They will have to suffer the consequences of their own stupidity.”

People might find themselves on the wrong end of a defamation or libel lawsuit.

“They are placing themselves in legal jeopardy, and they are doing absolutely nothing to help the investigation,” he said.

Police say the man is the main suspect in the murders of 14-year-old Liberty German and 13-year-old Abigail Williams. Their bodies were found near the Delphi Historic Trails on February 14 after they were reported missing by family. Police later released a recording of a suspect saying “down the hill.”

According to police, there are no arrests at this time, and Riley could not comment as to whether they are close to making an arrest. But he assured everyone this is not a cold case, and they’re still getting around five to 10 tips every day. “We’ve always felt that we’re going to solve this case,” Riley said.