WWPD

     Somebody just put a .38 slug into the back of Mr. Toad’s brain, and I’m investigating the murder.

     I have half a dozen suspects, all of whom had plenty of motive and the opportunity to deal Mr. Toad permanently out of the game. But only ONE of them had the means -- in this case, the .38 calibre firearm. But the weapon is not at the scene, and subsequent searches, properly conducted with a warrant based on probable cause, supported by oath or affirmation and describing the particular places to be searched and items to be seized, turn up zilch.

     Then along comes a source who says he has in his possession the murder weapon, and bestows upon me a handgun in a plastic bag.

     “Ratty killed Mr. Toad,” he tells me. “Here’s the murder weapon.”

     Wonderful.

     Case closed, right?

     But suppose this informant is a junkie, a career criminal with a long history of perjury. Should I tell him to stick that gun into the orifice of his choice and get out of my office?

      What if he’s a pimp or a child pornographer, or worse yet, a politician?

Suppose the informant is a “known” communist, or fascist, or a member of the local PTA. Would his belonging to such a despised group be a good reason for me to give him and his alleged evidence the boot?

     Suppose the informant wants a hundred bucks for the evidence. Or what if the informant is one of the suspects who clearly has a vested interest in casting suspicion on someone other than himself? Is that conflict of interest reason enough for me to shit-can the baggie?

     Don’t be a sap.

     No matter who brings me the evidence, no matter why they bring me the evidence, I’m going to take it, and I’m going to run a ballistics test and dust it for fingerprints, maybe look for DNA.

     Either the ballistics will match the murder weapon or the ballistics won’t match the murder weapon.

     Either we get fingerprints or we don’t, and those prints will either match one of the suspects or not.

     If the gun in the bag is the murder weapon, and it has Ratty’s prints all over it, I don’t care if Adolf Htler brought me that evidence; I’m going to have a little chat with the old rodent.   If the gun in the bag isn’t the murder weapon and/or doesn’t have Ratty’s prints on it, I don’t care if Mother Teresa brought me the evidence; it doesn’t support an arrest of Ratty for the crime. In short, I’m going to assess the evidence on its own merits and nothing else.

     If you summarily reject evidence because you don’t like the person who brought it to you, or if you automatically accept evidence because you like the person who brought it to you, you’re not a detective. You're a mark.

    If your theory of the crime is “Ratty Murdered Mr. Toad” then all the evidence must support that theory.

     If the gun in the baggie has Ratty’s prints all over it -- but it’s a .45 and not a .38, the evidence doesn’t support busting the old Rat. It isn’t the murder weapon.  “If he owns a .45 he probably ALSO owns a .38,” says my informant. 

     Yeah? Prove it. Bring me the .38.

     If the pistol in plastic is a .38 and the ballistics all match up  so we’re sure it’s the murder weapon, but the prints on the gun  -- all nice and clear -- don’t match Ratty’s, then the evidence  doesn’t support an arrest.

     You have to account for all the evidence. You can’t just cherry-pick the evidence that supports your theory while ignoring evidence that refutes your theory.  Cherry-picking is what puts innocent people on death row.

     Now, what about that ballistics report?

     The fingerprints?

     How “expert” is the expert running the tests? Did he/she get his training in a one-hour on-line course from Joe’s Investigative Academy and Taxidermy School?  Or does he have hundreds of hours of advanced training and a couple decades of experience? Regardless of his bona fides, what’s his batting average? Have 50% of his analyses later been proven to have been incorrect? What if he’s positively matched fingerprints to ALL suspects who were Black but NEVER to a suspect who was White?

     When you’re relying on an expert to determine the truth of a particular fact, NOW it’s perfectly acceptable -- in fact NECESSARY -- to be sure that your expert is really an expert and conducting his part of the investigation objectively, impartially and in accordance with the best scientific methods and procedures, and not tainted by other influence.

     Once you examine all the evidence, you can then piece it all together to formulate a theory of the crime. Your theory MUST be based on the evidence and nothing else, and you must include all the evidence without leaving anything out just because it doesn’t fit your theory.  If it isn’t Rat’s prints aren’t on the murder weapon, and a dozen eyewitness say that Rat was in custody for drunk driving a hundred miles away at the time of the murder, you don’t get to say, “I STILL think it was him. He’s a RAT.”   You let the evidence lead you to formulate a theory of the crime -- not the other way around.

     The world is full of people who want you believe all kinds of things. Some are definitely true. Some are probably true. Some might be true. Some are pure bullshit.

If you’re not going to be an easy mark for every grifter, hustler and political hack who has a nice smile and a good suit, “common sense” ain’t gonna cut it.” You’d better learn how to act rationally and not emotionally.  “

     "Rationally" means you believe what is supported by good evidence and ONLY what is supported by good evidence.

     "Emotonally" -- or "Irrationally" --  means you believe what is not supported by evidence, or even what is contradicted by good evidence.

     The rubs lies in the fact that human beings (except for psychopaths) are hard-wired with emotions, installed at the factory. Emotions are universal, instinctive, automatic and effortless.

     Critical thinking is not. It’s an acquired skill, like playing the cello. It is rare, counter-intuitive, and requires conscious effort and regular practice.

     But it’s worth your time.

     Consider it intellectual self-defense.

--aac