But why is that million dollar reward not bringing this person forward?IMO, they are hoping for someone who has heard or seen something but was not "involved". Like a GF (or ex GF) or friend or parent. In the Tracey Harris cases there was a person(Dawn Beasley) who stayed silent for 30 years because her own husband, who was not a POI, was the killer.
I'm recalling a lot of cases where nothing moved forward until someone talked -- and often not even for any reward.
(for example in the Pamela Smart case, an anonymous call to LE came from a pizzaria worker who had been told by a delivery driver that another worker (a minor) was Pam Smart 's student and had said knew she'd known about the crime in advance, and had been in on the murder for the life insurance money. Of course broke the case wide open.)