I wonder to what extent the Manley's have been cooperating with LE. Publicly they have denied to have any knowledge about the growing operations. I find this hard to believe. For example, BJM was a regular visitor and must have seen or smelled something. Perhaps they are more forthcoming when talking to police but I don't think so. The grow operations may be very important in the investigation, and anything less than complete disclosure would hamper the investigation.
The reports in the media about how the bodies were found by the Manley's seem to contradict the 911 tape. The police may suspect some kind of cover-up. Perhaps that is why the truck of LM's son was collected by LE.
Now that the funerals are over, the gloves of LE may come off. If LE feels that the Manley's are not fully cooperating, and they have found proof of a some kind of cover-up or tampering with evidence, they may decide to arrest someone. JMO, of course.
If LM says that he feels that his family is a target of LE, then this may be because they are. However, I think they are not be the only target, and they are not the main target. We will see what happens. I am curious to see how the relationship between LE and the Manley family further develops.