Authorities released new audio and video footage Monday in the yet-unsolved 2017 case of two teenage girls who were murdered while hiking on a trail near Delphi, Indiana, warning residents that the killer likely lives or works in the small town.

Although the police have not yet made any arrests in connection with the murder, Indiana State Police Superintendent Doug Carter told residents in a Monday press conference that “We believe the person is from Delphi, currently or has previously lived here, visits on a regular basis or works here.”

Carter addressed the killer directly, close to tears throughout his prepared statement: “We believe you are hiding in plain sight,” he said. “We likely have interviewed you, or someone close to you. We know that this is about power to you, and you want to know what we know. And one day, you will.”

“What will those closest to you think of you, that you murdered two little girls,” he added. “Only a coward will do such a thing.”

The girls, 13-year-old Abigail Williams and 14-year-old Liberty German, were dropped off on a local hiking trail by family members at about 1 p.m. on Feb. 13, 2017. At 2:07 p.m., German posted a snapchat photo of Williams crossing the Monon High Bridge.

The girls were supposed to meet German’s father at about 3:15 p.m., but they never showed up. Police quickly launched a manhunt—and the following morning, cops found the Delphi Community middle schoolers’ bodies near Deer Creek, about half a mile from their last known location. It’s not yet clear how the girls died.

“To the murderer: I believe you have just a little bit of a conscience left,” Carter said Monday. And I can assure you, that how you left them in that woods is not, is not what they’re experiencing today.”

In the aftermath of the murders, officials released a low-quality, grainy photo of a man in jeans and a thick blue jacket, as well as audio footage from German’s phone in which a man can be heard saying “down the hill.” It’s not clear if the man in the footage is the same person who ordered the girls down the hill.

“ This person’s evil. This person is a monster,” lead investigator Sergeant Jerry Holeman said in a TV interview. “This could happen again. So if you’re holding that information for whatever reason, you need to think of that. This could happen to your niece, daughter, cousin, sister.”

On July 17, officials released a sketch of the suspect, who was described as 5 feet 6 inches to 5 feet 10 inches, weighing 180 to 220 pounds, with reddish brown hair.

During the Monday press conference, authorities released new evidence from German’s phone: an 11-second audio clip, in which “down the hill” is repeated a few times, and a video clip of the suspect taking two steps forward on the bridge. Carter asked residents to carefully scrutinize the suspect’s voice and gait for leads.

Authorities also released a markedly different sketch of the suspect, asking residents to consider the old version “secondary.” Carter said that the suspect is likely between the ages of 18 and 40, although he may appear to be younger.

In September 2017, police arrested 31-year-old Daniel Nations as a potential suspect, after he was arrested in Colorado for threatening people on a hiking trail with a hatchet. But Indiana authorities later downplayed the arrest, stating that Nations was not someone “they care a whole lot about.”

Despite tens of thousands of tips and a $230,000 reward, the case remains a mystery.

“We’re all frustrated,” Williams’ mother Anna told ABC News just before the second anniversary of her child’s death. “It might still feel like we’re in the same place, but I think of how many tips we’ve gone through, how many are still out there, still coming in, and I have hope that we are on the right track.”

Carter addressed the victims’ families directly during his statement. “When I take my last breath on this earth, I’ll be thinking of them,” he said. “Never in my career have I stood in front of something like this.”

“We are just beginning,” he said in conclusion. “We will not stop.”