Unless BL confesses it is unlikely there is any direct evidence.
Correct me if I am wrong, but I believe
Direct evidence is essentially a material fact that doesn't require inference: eye witness to the crime as it is occurring, confession to the crime from the suspect, or photographic/camera evidence of the crime as it is occurring. That's pretty much it.
There were no direct witnesses and there is no camera footage that we know of documenting the crime as it happened. It's doubtful that BL will confess if he is captured.
So, I think it's reasonable to assume that if the case goes to trial, the majority of the evidence presented will be circumstantial. Forensic crime scene evidence is circumstantial. So are GPS data and phone records and pings, and digital data such as the camera footage of the van at Spread Creek dispersal camp etc.
There's a really great explanation here:
https://askanydifference.com/difference-between-direct-and-circumstantial-evidence/