"We tried Christmas but that didn't make sense to us so we went Halloween, yeah!" said Lab Director Alex Karagianes with a laugh.
And why not? It's a macabre time of the year.
Jim and Carol Calhoun and their daughter and grandkids, three generations, all came on Wednesday.
The best haunted house in the Bay Area - the San Mateo Co. Coroner’s office! Halloween open house and tour!!😎 abc7newsbayarea pic.twitter.com/aBrEMUUWAh— Vic Lee (@vicleeabc7) October 30, 2019
"Great experience being able to learn about how they do a lot of the stuff to solve mysteries," said grandson T.J. Enos.
Ariel Flores came for another reason.
"I'm actually a forensic science student at San Jose State hoping to get a job at the coroner's office," she said.
A big investigation going on at the coroner's office on Wednesday - who attacked and killed the scarecrow?
There's a crime scene with evidence and clues, all in plain sight of the tour participants who listen to a quick lesson from a talking skeleton at the forensics lab on the importance of DNA.
Then a witch briefed everyone on drug testing - did the scarecrow die of fentanyl opiate poisoning?
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Next there's a tour of the finger printing lab - were there any prints lifted from the crime scene or prints of the killer? Was he shot?
At the firearms unit, some 1,400 guns and rifles of every type stored in a locked compartment.
Ballistics tests are run on the bullet and gun used by the killer.
Finally, the last stop is the garage where the amateur sleuths can get a quick review of what they learned and the clues exposing the killer.
I asked the Calhoun's and their extended family, "Who dunnit?"
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"I think it was the monkey," said 11-year-old Katherine Enos.
Why was it the flying monkey?
"The knife and the blood on the clothes," concluded Suzanne Enos, Katherine's twin sister.
"Have a bloody good time" on Halloween!