Did Murdered Indiana Teens Capture the Voice of Their Killer?

A voice can be heard saying "down the hill" on a recording on Liberty German's cell phone.

One of the teenage girls killed while hiking last week in Indiana may have captured the voice of the male suspect in their deaths, police said Wednesday.

“This young lady’s a hero, there’s no doubt, to have the presence of mind to activate the video on her cell phone to record what we believe is criminal behavior that is about to occur,” Indiana State Police Sgt. Tony Slocum said Wednesday.

Read: Police Name Mystery Man Caught on Surveillance as Suspect in Murders of Teen Hikers

The audio was recorded on 14-year-old Liberty German’s cellphone. She and her 13-year-old friend, Abigail Williams, disappeared on February 13 while walking a popular set of trails in northern Indiana.

A man can be heard saying “Down the hill, down the hill," on the crackling audio. German was somehow able to activate her phone during the last moments of her life, and also captured video of a man walking nearby.

Police say that man is their prime suspect in the slayings. Officers have not ruled out the possibility of other suspects.

Read: Footage Shows Mystery Man Who May Help Cops Shed Light on Murders of Teen Hikers

They released the audio at a Wednesday press conference, asking for the public’s help in identifying the voice.

Volunteer searchers found the girls’ bodies in a wooded area off the trails two days after they were reported missing. A relative called police after the teens failed to appear at a designated pick-up spot.

Police have released only a still image from the video and a loop of the words “Down the hill” in repetition.

Watch: How a Social Media Photo May Have Tipped Off Predator That Killed Girls on Hike