The biggest clues in this case seem to be the pictures and voice capture.
http://www.theindychannel.com/news/crime/delphi-indiana-what-to-look-for-in-a-delphi-suspect
Greg Massa, the assistant special agent in charge of the FBI's Indianapolis field office, provided some information at the press conference that does seem to be the beginning steps toward a profile (see link above). To me, what it means, is this could be a person who had some psychological effects of the crime afterwards and this could be observed in his behavior. I know it's a longshot after two weeks, someone could be putting these pieces together, but you never know.
Massa quotes:
"Just think if you had an interaction with an individual who inexplicably canceled an appointment that you had together," Massa said. "Or an individual called into work sick and canceled a social engagement. At the time, they gave what would have been a plausible explanation. 'My cell phone broke' or 'I had a flat tire on my car.' In retrospect, (that) excuse no longer holds water."
Any other behavior that might be considered suspicious, such as somebody acting differently since Feb. 13, that should be a red flag.
"Did (an) individual travel unexpectedly?" Massa said. "Did they change their appearance? Did they shave their beard, cut their hair or change the color of their hair? Did they change the way they dress?"
The FBI is also looking for anybody who may have changed their regular behavior after Feb. 13. He said to try and remember anybody who:
Has a different sleep pattern now
Started abusing drugs or alcohol when they wouldn't have beforehand
Has become anxious or irritable
Has followed this case and what the media is releasing with a sense that is "not normal"
Has been having ongoing conversations about where they were on Feb. 13
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This may suggest some research was involved in Massa's advice to the public for characteristics to be aware of in the POI. IMO, these characteristics are based on research from similar offenders.
Putting Massa's statements (about the possible characteristics of the killer after the murders) with the pictures and voice recording, you may have a better totality of understanding where the investigators were trying to lead the focus for the public to pay attention.