I only saw the last part of the show, but it seems the "incognito" person believes the killer is a detail-oriented, computer-savvy auto mechanic who relocated his business (from Ocean Pkwy) after the GB4 were found.
I feel as if I must have missed something more.
The incognito person was saying they had an idea of a suspect. They were a LI native and talked about a local mechanic who is very organized in his shop every nut and bolt is in place, he's detail oriented, and good with computers. Speaks in a calm, cool voice like Melissa's sister described.
She said his demenor changed when the bodies were found. He moved locations of his shop, he got irritated with customers and lashed out being rude, his work suffered and he slacked on the type of mechanic work he would put out for customers.
Apparently dolls called "time out dolls" (a google search reveals some info on them--haven't done much research yet tho) but they were placed at the scene of the memorials on Ocean Parkway and then quickly removed the morning after. Incognito says she's seen similar dolls in Mechanics house.
In my google search I read these dolls are often found at craft shows or at auto shows to show them peaking under the hoods of cars to mimic a mechanic fixing the car.
Honestly, it's the first time I heard the detail of the dolls. Dark Minds showed a picture of the dolls draped over some of the crosses...I remember one was Amber's. If the episode pops up online I can screencap it.
I'm still not convinced incognito is an actual person and not an undercover from investigators dropping hints because they know the killer was probably watching. This case gets very little news coverage anymore. I know Phelps is a clown but at least he shines light on cold cases. It's been a few years since the bodies were found and there have been no new confirmed kills. It's basically cold. We know investigators keeps certain facts about the case hidden so the killer can confirm them later on if caught, I can't help but think law enforcement dropped the hint about the dolls to try to spark new leads. The dolls are odd, maybe someone recognizes them.
I think the dolls are probably bagged sitting somewhere in an evidence box as of now.