the man blew over the DUI limit. cross and type is not conclusive as others can have the same blood type. The only conclusive way to prove with that little of blood would be DNA testing. you learn a lot when you have forensic scientists as friends.
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Yes, but the chances of the driver and the passenger having matching blood types is pretty small (yes, I know there are only four types of blood, but combined with other blood factors...). It would be a quick and less costly way to determine who was driving. It could be followed by...

Ahh, nevermind. It's really not that important.