Forensics C

[pikachu4919]

Forensics C: Given a scenario and some possible suspects, participants will perform a series of tests which along with other evidence or test results will be used to solve a crime.

Forensics Wiki

Forensics Test Exchange

Recommended Lab Equipment List for Div. C

Past Threads: 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020

Past Question Marathons: 2015, 2016, 2017, 2018, 2019, 2020

[tennis2019]

Rip Woz's website, a crushing loss. time to use wayback machine lol

Edit: After a little digging, I found it just migrated to here.

[WangwithaTang]

Rip Woz's website, a crushing loss. time to use wayback machine lol

Edit: After a little digging, I found it just migrated to here.

The links are don't work for me there. Do they work for anyone else?

[WangwithaTang]

Rip Woz's website, a crushing loss. time to use wayback machine lol

Edit: After a little digging, I found it just migrated to here.

The links are don't work for me there. Do they work for anyone else?

None of the links have been updated, so you'll have to change them by hand. Change the http://mypage.iu.edu/~lwoz/ at the beginning of the url you want to https://lwoz.pages.iu.edu/ and all of the information should still be there. It's a little annoying, but it's a solution.

[Galahad]

Does anyone have a really good resource to understand Mass Spectrometry/how to read it? I get the idea behind it but I'm still very much confused on how to derive chemical formulas from it

[SilverBreeze]

Does anyone have a really good resource to understand Mass Spectrometry/how to read it? I get the idea behind it but I'm still very much confused on how to derive chemical formulas from it

I would like to know this as well. For now I've been looking at peaks decreasing in intervals of 14 and using those for number of carbons, then BSing the rest.

[ZachMUHS]

*rant incoming*

So Northridge happened today, and forensics was a hot mess.

Instead of giving descriptions of the unknowns and descriptions of their test results, we were given a 20 minute long video of the ES doing the tests. There was also a 40 second video of the ES doing a burn test on the single fiber sample which all we were provided was a visual of the burn test, no description of smell or any tactile information about the fiber and the bead it formed. As for plastics, we got 6 pictures of each plastic in each differential density solution. In concept that sounds like it would work, but the pictures were so low quality you could barely see the little plastic bead in the beakers, and in some pictures, it was completely invisible.

So, to anyone who might be thinking, "Well that sounds a lot better than just dry labs with no actual lab participation", in a way it was, but largely it was even worse. In theory, I think this is a really cool idea, recording the tests on each unknown, however, in practice it's too ambiguous. Every team does things differently, so when you prepare for three months doing it one way to be provided with a completely foreign method is quite jarring and unrewarding.

To improve the concept, ahem DON'T TEST ALL 10 POWDERS IN ONE VIDEO. I think this could really work if each powder had its own video, but when they're all in one video it just doesn't work (FYI, the video would run one test on all 10 powders then move onto the next test e.g. ES added water to all 10 powders and showed the results. ES then added HCl to all 10 powders and then showed the results. . . repeat for all tests in forensics). As for the plastics, just SAY what happened. I don't think there was ANY need to take pictures of the float tests; all it created was confusion and ambiguity.

I won't talk about the rest of the test's quality or else this post might be three times as long, but my main grievance was how confusing and inefficient the ID'ing was for this test. Once again, I really like the concept of recording the actual tests, but in practice, it just doesn't work as well as one might hope.

So to any forensics ES's and writers who read this post, please please please do not do this. Or if you do, at least drastically improve upon it. As a competitor, it's extremely frustrating when presented with something this confusing.

*thank you for listening to my rant*

[BobbyJoe]

Hey!

Hope everyone's season is going well. I wanted to ask how everyone is identifying their powders? Is it just me or is it really difficult this year? Any resources/tips? I have the charts of the results and all but it just never seems to be right.

[CPScienceDude]

Hey!

Hope everyone's season is going well. I wanted to ask how everyone is identifying their powders? Is it just me or is it really difficult this year? Any resources/tips? I have the charts of the results and all but it just never seems to be right.

Unfortunately, everyone kind of has different results for their tests and their own way of describing things. My biggest piece of advice would be, if it's possible, practice with your partner in person doing the actual tests on the powders. Consistently practicing with the actual flame test, iodine, HCl, NaOH, etc will continue to develop your understanding of the powders and how they behave. If this isnt an option, continue to research the powders and their properties. Doing so will also help develop your understanding of their behaviors. One more thing I always say is take a lot of practice tests. The more exams you take as practice, the more material you're exposed to. From this, look up anything you don't know and analyze your mistakes and why you made them eg. "was my sheet wrong?", "this was brand new to me, I'm going to research it and put it on my sheet for next time.". Unfortunately, as I said before, everyone has their own way of describing the test results in forensics, and because of this, some powders may not follow the behavior you might expect them to. There really isn't a way to prepare for this, at least not one i've thought of, so in a sense a bit of luck goes into whether your powders behave the same as the event supervisor's.

Anyway, that's all the stuff that came off the top of my noggin. Hopefully that was somewhat helpful!

[BobbyJoe]

Understood. Thank you!