Who abducted and killed Rachael Runyan?

On August 26, 1982, Rachael Runyan was playing at a park with her brothers, just 15 feet away from their house. Their mother was inside the kitchen making lunch. A man came by and lured her to his car with the promise of bubble gum, then drove off with her, leaving her brothers behind. He drove away in a 4-door blue car with wood stripes down the side. The suspect was described as a slender black male, 6 feet tall, age 25-35. A composite is available here.

24 days later, her naked body was found hog-tied in a creek off a dirt road in Morgan County. She had been molested and tortured before being murdered.

Two years later, a message was found in a local laundromat. The message said "Beware. I'm still at large. I killed the little Runyan girl! Rember beware!!!" Below this was an upside-down cross and the numbers 666. Here is an image of the message.

Her murder remains unsolved. Utah created the Rachel Alert as a child abduction alert system, which was later renamed as the Amber Alert to conform with other states. Here is a video from Rachael's mother.

Here is a previous post made about this case made by /u/luckystrikeserena. I'm going to borrow some text from that post:

Sunset Police Chief Ken Eborn said this week that detectives are currently checking out a former Utah resident — now living in Pennsylvania — who has been a long-time person of interest in the case.

The girl's mother believes the Pennsylvania man may be her daughter's killer. "This same guy keeps surfacing," Runyan-Simmons said. "You can't help but keep your eye on him."

The man, now 50 years old, came to the attention of police again because of an Amber Alert issued last year [2011] in Pennsylvania after he allegedly took his child following an argument with a girlfriend. The child was safely returned and the man, was later charged with domestic violence related crimes. He also has a violent criminal history in Utah, according to court records.

Police, who have chosen not to release the man's name, say he lived in the Sunset area at the time of Rachael's abduction, and also has lived in New Mexico, Arkansas, and Pennsylvania.

I did some sleuthing and identified this POI from Pennsylvania. I won't mention his name, but it's easy enough to find by doing a search for the child involved in the 2011 Pennsylvania Amber Alert. If you take a look at this crime blog, you'll notice some strange comments, possibly made by the POI, his girlfriend, or someone impersonating them. I've posted about this before on reddit and quickly received some very nasty and threatening messages. I'm not sure if it's from the same person on the blog, but they used some of the same phrases. I personally believe it's someone trolling, but I thought I should mention it.

What do you all think of this case? This last year we've seen so many cases being solved. It gives me hope that this will also be solved some day.