Transcript for Delphi police reveal new details in murder of teen girls
Right now we get to new developments in that Indiana murder mystery and released new images and audio of the man. Alex Perez has the latest. Reporter: Hey, good morning. Authorities believe they will find whoever took the girls from this trail. They believe their suspect lived or maybe even still lives in town. To the killer, who may be in this room, we believe you are hiding in plain sight. Reporter: This morning a determined police department and a small Indiana community on edge for two years with a killer on the loose. We know this is about power to you and you want to know what we know. One day you will. Reporter: Authorities investigating the murders of 13-year-old Abby Williams and 14-year-old Libby German sharing new evidence. The teenagers were murdered back in February of 2017. Last seen on this hiking trail snapchatting near this bridge in delphi. Libby police believe captured this image of the suspect on the same bridge because she feared they were in danger. Authorities for the first time saying they believe the killer is likely a local. Watch the mannerisms as he walks. Do you recognize the mannerisms as being someone you might know? Reporter: The man's voice also captured on audio and in a newly released clip we can hear more of the suspect's chilling voice talking to the girls shortly before they were killed. Down the hill. Down the hill. Reporter: Initially they released this sketch but now releasing this younger looking image saying the man is between 18 and 40 years old. For more than two years, you never thought we would shift gears to a different investigative strategy, but we have. We likely have interviewed or someone close to you. Reporter: The hunt for the killer is now intensifying? When he said he could very well be in this room, that he could be under our noses and the people here that live in delphi, I mean, that's frightening. Reporter: Authorities stressing they believe the suspect appears to be much younger than he actually is. They're hoping this newly released evidence will be what they need to crack the case. Thanks very much. Let's bring in Callahan Walsh from the senate center for missing and exploited children. Pretty dramatic to see the investigators talking directly to the person they think did this. What do you make of the shift in strategy? Well, I think they have some new information. I think they have a new eyewitness that came forward. You see the new sketch so they have more information there. They're also asking about a not specifically a car but a vehicle that was parked near that trail head which I think they believe is the vehicle of the suspect so with new information they're shifting gears and putting this out to the public making sure they're keeping this case alive. I think that's so important. It is so important. The sketch is such a drastic difference from the one that we saw originally so as you're saying you feel there's somebody new that possibly came forward. The sketch isn't created from the video. A sketch like that is mostly done when someone is describing what a person looks like. It's not a computer generated image from that video or anything like that. And so it could be somebody they interviewed in the past or somebody new who came forward and looking inwards at the community hoping that others come forward as well with any information. You know, people sometimes think their tip may be insignificant and don't say anything but it can oftentimes be the key that unlocks the door to justice. Investigators have had this from the start. Why release it now? They're hoping people can look at the gait. How he walked and try to determine maybe that looks like a relative that they have or somebody that they know. So, again, leaking a little bit more -- I wouldn't say leaking but releasing a little more information really keeps the community invested in this crime and if anybody out there who did know anything maybe weighing on their conscience they're seeing it again and getting a reminder, you need to do the right thing. That press conference was really something to watch. The police looking right into the camera speaking directly to the killer calling him a coward saying they think he could be in the community. What's the strategy behind that. Oftentimes when individuals commit crimes they will stay close to the investigation. We see people burn down houses and watch the firefighters put the fire out. Same with crimes like this so he's likely very close to the investigation and also trying to take the temperature of the investigators to determine what they know and how close and how hot on hit trail that they are. So it's not very -- it's not unlikely he could have been a volunteer who helped in the search, a firefighter, paramedic, somebody that's involved in this investigation. It's a tight-knit community. Not a very big area and hoping that if he's there at the press conference or if he was involved -- You think that's possible. Absolutely. Didn't they take the names of everybody there. They did. Which is usual, very unusual and a sign they think this guy is right there in the woodwork. Thanks again for coming in. An ABC news exclusive.
This transcript has been automatically generated and may not be 100% accurate.