...alternatively, it was reported that there was detergent/cleaner in the trunk of the car. If there were bleach in the detergent, as is often the case now, and it was used to clean the trunk, or even spilled in the trunk, it may have reacted with the post-mortem urination from the body also stored there
http://www.answerbag.com/q_view/20233
I know the reports say something like 'elevated' chloroform levels. So this is a stretch explanation for now. Really need to know if we're talking 10% higher than background or 100% higher than background to see if this is plausible.
I'm not sure you can just go get chloroform off-the-shelf.