Going to add some specifics in hopes it may answer some of those questions...
- Feb 15, 2017 LE released the image of who is now known as BG. Police do not call the man in the photo a suspect but say they would like to talk with him.
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Investigators want to talk with him about what he may have seen. They would also like to speak with anyone who was parked at High Bridge Trail Head on Feb. 13, between 1 p.m. and 5 p.m."
Police ask for assistance in identifying man seen walking on trail where Delphi teens went missing
- Feb 19, 2017 LE announce that the man in the photo released on February 15 was now a suspect.
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During the course of the investigation, preliminary evidence has led investigators to believe the person, in the distributed photo, is suspected of having participated in the murders of Abigail Williams and Liberty German," said state police in a press release."
Also
"Sgt. Tony Slocum said the person pictured is “our suspect we are considering at this time" and police would like to arrest him."
ISP: Man in photo considered Delphi suspect
- Feb 22, 2017 LE release audio that was captured on Libby's phone. LE leave open possibility of other suspects and indicate uncertainty over whether or not the voice on the audio belongs to the man in the bridge photo.
"During the news conference. Sgt. Tony Slocum said the search continued for a man seen in a photo. Investigators revealed that the photo also came from Liberty German's phone. They said it's possible the voice in the recording is that of the man in the photo. They also acknowledged that it's possible more than one person may be involved."
Slain Delphi teen recorded audio, video of man wanted in homicide investigation, police say
- April 22, 2019 LE releases new sketch and says voice on audio is that of man in the photo.
"Please keep in mind that the person talking is one person and is the person on the bridge with the girls" Carter said. "This is not two people speaking. Please listen to it very, very carefully."
ISP says new audio, video and sketch shows Delphi killer
I have seen no public explanation as to why the change in certainty/confidence that it is all the same individual.