Heidi Blake did actually do some work for her podcasts - tracking down Nick Milbank. But a lot of the "journalism" around the case is just acting as PR for Bamber and the CT with no accompanying analysis.
HB probably understands the breadth of the case but not the depth. If she did she wouldn't be beating the drum about the late Nick Milbank/999 call unless of course she is being disingenous and/or needing to appease her editor by justifying time spent etc. I don't think there was much 'tracking down', he appeared in many public records. But I did admire the fact she turned up at the homes of the Eatons and Boutflours putting them on the spot
DB is probably the weakest link. He often sounds emotional. He has commented about JM not saying anything in the early stages. He knows he didn't find the silencer in the state he later claimed. It appears there is now no love lost between the Boutflours and Eatons. DB commented to David James-Smith he could not understand how AE lives at WHF. DB was (is?) religious. He lost his son at 13 yoa in tragic circumstances. This might prey on his mind as pay back for his sin in perjuring himself at JB's trial.