Does this spell cause the wand to only reveal its very last spell or could it be used to look at a larger number- say the last ten or twenty spells cast by the wizard/witch?

 

The only time it was used in canon it only revealed the last spell. Of course, its likely that can show more, otherwise it would be a fairly useless spell in forensic matters (as its use seem to lie).

 

Deathly Hallows:

If Harry isn't just babbling, then there is a way to show more than just the last spell.

 

Probably relies on intent, like a lot of other magic.

 

Which might lead to a battle of will between the person casting the spell and the one that 'owns' the wand.

We know that theres a link, a bond if you will, between a wand and his master. So maybe the person by allowing the wand to be examined(instead of getting disarmed before the spell was cast) could force the wand to skip a few spells which he would not want anyone to know about.

 

Having a pale imitation of the spell come out of the wand might work, or the incantation sounded out in the voice of the caster. That has problems with silent casting, but I can't think of anything else atm.

 

I can't really see any use of a spell being 'forensic' in canon HP. For AUs like a lot of the February competition entrances you need more specific, useful spells and you change them to suit that purpose.

But canon magic is retarded, and exists to make the world quirky and unusual, thus a spell like Priori Incantatem relatively useless for actual investigation. Even with a superb analysis like Sesc's there, you can never fully tell what a spell is meant to do or its specifics like what colour they are excepting Stupefy and Avada Kedavra, those two most used spells by writers.

So in answer to the original question, Canon is inconclusive. If your story requires it to be able to see more spells, it can and vice versa.

 

Works very well, if you want that type of spell. But I will stick to my guns that in canon all spells are basically useless tricks Rowling uses to spice up the universe. Even if the use of a spell seems obvious to you or me, it was likely just invented to achieve a plot point, not actually having any true purpose whatsoever. Apart from the Unforgivables and Stupefy, getting any real use out of spells is extrapolating. Though to be fair, you've done some great extrapolating and if there should be a baseline for P.I., I think yours should be it.

 

I think the real problem here is that it doesn't show why or on whom or on what the spell was used. Whether it missed its target or not is irrelevant if you're casting it at a fellow human being: attempted murder gets you put away for a long time just as murder does.

The real problem is that if you were defending yourself against a non-human that was attacking you, there's nothing illegal about it. However, it still says you cast a killing curse. How do you prove you weren't casting it at people?

The wizarding world seems like a guilty-until-proven-innocent kind of place (unless you've got cash). Maybe "I WAS IMPERIUSSED!" works?

Anyway . . .

Priori Incantology?

 

I would have said Deprehentology or even Depremency (From deprehensio; act of coming upon and catching). Partly because it sounds awesome, but also because you could use it as an umbrella term for all Magical CSI-esque techniques.

EDIT: Also Sesc your post was 44444444. Which I guess is kinda interesting

 

You go go another route and use something similar to what we did in Physics, where you could identify the elements found on other stars and planets by using the emission spectrum (is it called that?).

 

The whole Priori Incantato -battle between Voldemort and Harry was a bit flawed anyways as Voldemort killed James first and then Lily and then tried to kill Harry, but there is no mention of the killing curse that hit Harry*. The fact that James came before Lily did is either an intetional error or a plothole. Intentional error in the sense, that either the James wasn't dead yet but died later and the magic knew that, or a plothole in that either he was dead or that Wormtail, who must have been at the Hollow to retrieve the wand, used it to kill James. Both cases are plotholes, because if Wormy was there, it simply doesn't make any sense why he didn't finish Harry off as well.

*It hit because of the scar and was then either redirected back to the caster or it was simply the backlash of Lily's protection that destroyed Voldemorts body and the house at Godric's Hollow. I doubt James was able to stall Voldemort that much to destroy the entire building, since Harry's nursery or what ever was still intact.

 

Not quite either any more, though "plothole" is the closer of the two.

James coming out first was an error that was noticed almost immediately. It was also corrected ASAP, which is why it's no longer a plot hole: other than the initial print run, all the newer printings of the book have Lily coming out first. My own (softcover) copy has the fixed text.

 

Chromathaumatology

Thaumaturgy is the art of making miracles/magic (blame John Dee for this one)
-ology for 'study of'
chroma- for 'color'

I'm all for it, including some version of the deletrius to 'wipe clean' a potentially incriminating wand. If you don't dig a spell, a potion would be cool as well- again, the lack of spell echoes only revealing that the (no doubt illegal) potion/spell had been applied.

Further, there may be secondary analysis spells, devices or concoctions a CSI: Hogsmeade team might specialize in.

 

So basically... The Colour of Magic.