State Police blood test results can take several weeks. The time lapse you set forth here seems a bit extreme. You might try contacting the Trooper(s) involved in the investigation for an update.
Definitely contact the trooper assigned to your case. Something doesn't sound right here - 4 months is way to long. I know the lab in Lima is backlogged from a case i recently handled.
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The short answer is "as long as it takes". But even though the PSP lab is terribly backlogged, this seems too long. I will assume that you have a legitimate interest in this case other than as a bystander. I agree with my colleagues that if so, you should try to contact the investigating trooper and ask for a status report on the progress of the case.
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