“I wonder if traces of substances such as chloroform would be detectable in the bone marrow or hair samples?”
Nothing that was used to drug her right before she died would show up, because it would take both time and repeated use for a substance to show up in bone marrow or hair. If it was a one-time incident, however, then depending on the drug or dosage it might not have even been fully absorbed into her bloodstream, much less any other organs or systems that would last longer, before death. I honestly don’t even know if chloroform would show up in a hair sample to begin with, as it’s not very common in this day and age - it’s more likely something like valium or some other narcotic was used, and those definitely show up in hair.
Perhaps the following can shed some light on the issue. I haven't actually checked any of it yet.
Hair drug testing:
http://en.wikipedia.org/wiki/Drug_test#Hair_drug_testing
Yahoo search results for "drug testing" + "hair":
http://search.yahoo.com/search?p=%22drug+testing%22%22hair%22&ei=UTF-8&fr=moz2