Phil Markel

And his children lost their father.

For years after Dan's murder, his parents, Ruth and Phil Markel, publicly fought to keep attention on the case and to maintain a relationship with their grandsons.

And the irony at the center of this entire case is almost impossible to ignore.

The conflict that prosecutors said motivated Dan's murder centered around where his children would live and who would have access to them.

We used some archive of them speaking at certain points about Dan, uh, during the investigation.

Um, and yeah, Phil Markel's speech at the end of Donna's trial, I think, really was just the obvious choice for how to end the series.

I think that he puts it so well that this was obviously a story which came from, you know- Donna Adelson's selfish desire to want to be close to her grandkids and have her own way, and in, you know, in trying to achieve that, she's actually just destroyed so many other families, and there are so many other kids, as well as her grandkids, who are without one or two of their parents, which is the real tragedy here.

There's still no, uh, accountability that has taken place with Charlie and Donna.

Robert testified that after Dan was killed, Donna called him with details about the shooting that made him uneasy.

He was also struck by what he described as her matter-of-fact tone and the family's apparent lack of curiosity about who had murdered the father of Wendy's children.

When Robert told Donna that he had spoken to law enforcement, she reportedly told him, "You don't know anything anyway," and their relationship was effectively over.

One of the most revealing aspects of this case is that the alleged control of the Adelson family did not begin or end with the murder.

The four-part series is produced by Curious Films for ABC News Studios and is directed by Sebastian Smith.

It includes a recorded conversation between former FBI agent Pat Sanford and Robert Adelson, as well as the first interview with June, one of Charlie's former girlfriends, who describes what Charlie told her about Dan's murder.

The series ends not with Donna or Charlie, but with Dan's father, Phil Markel, reflecting on what this fight over two children ultimately cost those very children.

Was it worth it? That is the question hanging over this entire case.