I don't think there is a ton of forensic evidence such as blood or DNA. There just needs to be enough to prove Suzanne is deceased, which could be just one small sample. I think the case is largely built on witness testimony, the actions of the defendant, cell phone communication, and other circumstantial evidence.I think there's a ton of it.
If there was a huge amount of blood, as well as DNA evidence linking BM to the murder, I don't think it would have taken a year to arrest him.
IMO