DELPHI, Ind. - Authorities released video of the suspect in the 2017 killings of two teenage girls that shows the man walking on an abandoned railroad bridge the teens visited before they were killed.
Indiana State Police on Monday also released a new sketch and an updated audio recording of the man suspected of killing 14-year-old Liberty German and 13-year-old Abigail Williams.
The video and the audio came from German's cellphone, and police have hailed the girl as a hero for recording potentially crucial evidence.
State Police Superintendent Doug Carter said during a news conference in the girls' northern Indiana hometown of Delphi that investigators believe the man is between the ages of 18 and 40 and either lives or lived in Delphi or works in the area.
Carter vowed that police will solve the case and addressed the suspect during his briefing, saying, "We believe you are hiding in plain sight."
The bodies of the girls were found in February 2017 in a rugged, wooded area after they went hiking near Delphi, a community of about 3,000 people roughly 60 miles northwest of Indianapolis.
Investigators said they were dropped off near an abandoned railroad bridge to walk around and "hang out." The girls were supposed to be picked up later in the afternoon, but did not show up there at the previously arranged time.
Following an extensive search, the bodies of the two girls were found the next day approximately one-half mile upstream from the bridge, authorities said.
Police have not released details of how the teens died.
Investigators initially released two grainy photos of a suspect walking on the abandoned railroad bridge the girls visited, and an audio recording of a man believed to be the suspect saying "down the hill."
Investigators have reviewed thousands of leads looking for the man. Police also previously released a composite sketch in July 2017 sourced from eyewitnesses who believe they saw the man in Delphi.
During Monday's news conference, Carter spoke directly to the suspect.
"The question to you: What will those closest to you think of when they found out that you brutally murdered two little girls, two children? Only a coward would do such a thing."
He added, "We have a witness. You made mistakes. We are coming for you and there's no place for a heartless coward like you to hide that gets his thrill from killing little girls."
The Associated Press contributed to this report. This story was reported from Los Angeles.