I've looked closely at what might be similar crimes going back 20-25 years in IN and nearby states. These types of crimes are rare, to say the least. Murders in broad daylight on walking/hiking trails are rare enough, a set of crimes involving the murders of two juveniles on or near a trail in broad daylight is rarer, still. Usually outdoor daylight abductions in rural areas happen along roadways, again, even those are rare.
This is an extremely dangerous individual, and I often wonder what other crimes he has done and/or may be be capable of. If he's targeted people on trails in the region, he must be familiar with those trails and how those trails benefit his quickly getting on to and off of them to commit his crimes.
JMO
I tend to believe that Abby and Libby were BG's first murders and that BG did not know the girls.
What we do know about murderers who are not domestic violence motivated is that they often have or will commit other crimes. They can be little crimes like shoplifting or they can be burglary, robbery, assault, or another murder.
Assuming BG is local to the area, a good pool of suspects would be people who have been arrested in the surrounding area over the year prior to the attacks up to the present day.
A possible investigative strategy would be to pull a report of all the people in Carroll,Tippecanoe and Cass counties who have been arrested for a crime from 2/13/16-12/11/19. Then start filtering that list.
1. Remove any females.
2. Remove any men older than 40 on 2/13/17.
3. Remove any men younger than 18 on 2/13/17.
4. Remove any men who are Asian, Native American, African American, dark skinned Latino, Indian or middle eastern.
5. Remove any men taller than 6'1".
6. Remove any men shorter than 5'5".
7. Remove men that were in jail on 2/13/17.
8. Remove men that had obvious facial tattoos as of 2/13/17.
9. Remove men that had any disability like an arm or leg amputation as of 2/13/17.
Prioritize for first review:
1. Men who attended Delphi Community High School.
2. Men who have a history of assault or sexual assault.
3. Men who have a history of mental illness.
4. Men who were in their 20's 2/13/17.
5. Men that have family in Delphi.
6. Men who have a history of unstable employment.
7. Men that did not own a car on 2/13/17.
Note: if there was SA then the history of the perpetrator having mental illness is less likely and and if there was no SA it makes it more likely that the perpetrator has mental illness so that detail would be further used refine the pool of men to prioritize for review.
My guess is that there will be less than twenty men that will fit in the first review list and BG would be on it.
MOO