Macro allegedly recovered a DNA profile in 2008. The same year they <modsnip>
The timing adds up; Get DNA, compare to existing suspects, rule them all out, scratch heads, check case notes, come up with new suspects <modsnip> and put together a public campaign in form of CIA episode.
But as you say he likely would have had to provide DNA (WA Police can enforce it from anyone they suspect of committing a serious crime). He told should have been ruled out. So why Macro so quiet for 7 years? And who's on their current suspect list?
Say this isn't a coincidence. Could the DNA profile and <modsnip> be linked, without Macro having enough to effect an arrest. In other words, could they have found a vague match (or a close match) but not enough to arrest, or is a vague DNA match enough etc. I don't know how this works.