Thanks, Truthwillsetufree. I hope you are right as to the thoroughness of the ME.
I am still unsure as to whether or not this testing could or could not have been performed. And also as to if it could have been performed, was it.
I found another publication,
The Complete Idiot's Guide to Forensics which states:
"Even in skeletal remains, diatoms may be recovered from bone marrow, thereby indicating death by drowning."
I'm not sure if this (long) google results link will work but I'll post it anyway:
http://books.google.com/books?id=Eh...marrow in decomposed skeletal remains&f=false
I guess we'll have to wait and see all the evidence and what all comes out at trial to be sure.