Anyone who was in the area where the missing Indiana teens' bodies were on Monday has been asked to to contact either the Indiana State Police or Carroll County Sheriff's Department immediately, particularly if they may have taken photographs.
Police said the bodies, found by search volunteers on Tuesday, are those of Delphi teens Abigail "Abby" Williams, 13, and Liberty "Libby" German, 14.
Their deaths are now being treated as murders.
Anyone who knows about the pictured man or has any information is asked to call the Carroll County Sheriff's Department at 765-564-2413, the Delphi Police Department at 765-564-2345 or the Indiana State Police at 765-567-2125.
Indiana State Police recently released two photos of a man described as Caucasian, wearing light blue jeans, a blue jacket, and a brown hat.
During the hike, Liberty posted a photo to Snapchat of Abigail walking on the bridge alone.
Sgt. Riley said a relative of one of the girls dropped them off Monday near the bridge and another relative had agreed to pick them up later. "I think people need to be cautious and careful", Riley said. "I don't know what time they ate last". You can remain anonymous if you request'.
Police and search parties scoured the base of the bridge and surrounding trails for hours before calling the search off due to darkness.
"We started going through all the social media things, looking at Facebook, has she talked to anybody, have the girls been talking with anybody, Snapchatting or whatever the kids do today back and forth", he said. "And in a small community when it happens, everybody goes berserk".
Search teams found their bodies Tuesday less than a mile from where they were last seen.
Now investigators are asking for the public's help to identify the individual.
"There is somebody out there who did this crime, and we're going to find them", Riley said.
Assistant Delphi Fire Chief Curtis Borden told the station the girls were discovered this morning but that it was "not good".