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AI Crime

Police Are Telling ShotSpotter To Alter Evidence From Gunshot-Detecting AI (vice.com) 147

An anonymous reader quotes a report from Motherboard: On May 31 last year, 25-year-old Safarain Herring was shot in the head and dropped off at St. Bernard Hospital in Chicago by a man named Michael Williams. He died two days later. Chicago police eventually arrested the 64-year-old Williams and charged him with murder (Williams maintains that Herring was hit in a drive-by shooting). A key piece of evidence in the case is video surveillance footage showing Williams' car stopped on the 6300 block of South Stony Island Avenue at 11:46 p.m. - the time and location where police say they know Herring was shot. How did they know that's where the shooting happened? Police said ShotSpotter, a surveillance system that uses hidden microphone sensors to detect the sound and location of gunshots, generated an alert for that time and place. Except that's not entirely true, according to recent court filings.

That night, 19 ShotSpotter sensors detected a percussive sound at 11:46 p.m. and determined the location to be 5700 South Lake Shore Drive - a mile away from the site where prosecutors say Williams committed the murder, according to a motion filed by Williams' public defender. The company's algorithms initially classified the sound as a firework. That weekend had seen widespread protests in Chicago in response to George Floyd's murder, and some of those protesting lit fireworks. But after the 11:46 p.m. alert came in, a ShotSpotter analyst manually overrode the algorithms and "reclassified" the sound as a gunshot. Then, months later and after "post-processing," another ShotSpotter analyst changed the alert's coordinates to a location on South Stony Island Drive near where Williams' car was seen on camera. "Through this human-involved method, the ShotSpotter output in this case was dramatically transformed from data that did not support criminal charges of any kind to data that now forms the centerpiece of the prosecution's murder case against Mr. Williams," the public defender wrote in the motion.

The document is what's known as a Frye motion - a request for a judge to examine and rule on whether a particular forensic method is scientifically valid enough to be entered as evidence. Rather than defend ShotSpotter's technology and its employees' actions in a Frye hearing, the prosecutors withdrew all ShotSpotter evidence against Williams. The case isn't an anomaly, and the pattern it represents could have huge ramifications for ShotSpotter in Chicago, where the technology generates an average of 21,000 alerts each year. The technology is also currently in use in more than 100 cities. Motherboard's review of court documents from the Williams case and other trials in Chicago and New York State, including testimony from ShotSpotter's favored expert witness, suggests that the company's analysts frequently modify alerts at the request of police departments - some of which appear to be grasping for evidence that supports their narrative of events.

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Police Are Telling ShotSpotter To Alter Evidence From Gunshot-Detecting AI

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  • glad for journalism (Score:5, Interesting)

    by fulldecent ( 598482 ) on Monday July 26, 2021 @05:37PM (#61622969) Homepage

    This what I call actual journalism.

    Can you imagine living in a world where these kind of things happen but nobody says anything publicly about it?

    • by rsilvergun ( 571051 ) on Monday July 26, 2021 @05:51PM (#61623011)
      The public defender who actually fought it. John Oliver has a good piece on public defenders and it's terrifying how little time they get to spend with clients. Especially when you contrast that with the nearly unlimited resources to prosecutors have.
    • Re: (Score:3, Insightful)

      by Luthair ( 847766 )

      I feel like the summary is a bit misleading, Vice doesn't seem to have a (ahem) smoking gun that the company is altering records to the demands of the police, or simply whether the automatic classification system isn't good enough requiring a human to be the arbiter.

      It does raise some other questions about how the company treats these reviews. If the reviewer knows the manual process was triggered by a request (or by a known incident) then they may have bias in determining the shots.

      • by XXongo ( 3986865 ) on Monday July 26, 2021 @06:46PM (#61623187) Homepage

        I feel like the summary is a bit misleading, Vice doesn't seem to have a (ahem) smoking gun that the company is altering records to the demands of the police, or simply whether the automatic classification system isn't good enough requiring a human to be the arbiter.

        Seems pretty damning to me. In the case discussed, the software gave one answer, and then humans at SpotShot changed that answer. Twice. (from page 29 and 30 of the court filing, https://pdfhost.io/v/RmCGSdFdT... [pdfhost.io] )

        In another case mentioned in the article: [vice.com]
        In 2016, Rochester, New York, police looking for a suspicious vehicle stopped the wrong car and shot the passenger, Silvon Simmons, in the back three times. They charged him with firing first at officers. The only evidence against Simmons came from ShotSpotter. Initially, the company’s sensors didn’t detect any gunshots, and the algorithms ruled that the sounds came from helicopter rotors. After Rochester police contacted ShotSpotter, an analyst ruled that there had been four gunshots—the number of times police fired at Simmons, missing once.

        Paul Greene, ShotSpotter’s expert witness and an employee of the company, testified at Simmons’ trial that “subsequently he was asked by the Rochester Police Department to essentially search and see if there were more shots fired than ShotSpotter picked up,” according to a civil lawsuit Simmons has filed against the city and the company. Greene found a fifth shot, despite there being no physical evidence at the scene that Simmons had fired. Rochester police had also refused his multiple requests for them to test his hands and clothing for gunshot residue."

        And then: they lost the original files.
        "Both the company and the Rochester Police Department “lost, deleted and/or destroyed the spool and/or other information containing sounds pertaining to the officer-involved shooting,” according to Simmons’ civil suit. “Greene acknowledged at plaintiff’s criminal trial that employees of ShotSpotter and law enforcement customers with an audio editor can alter any audio file that’s not been locked or encrypted".”

        If that isn't damning testimony to you, I'm not sure what I can say to convince you.

        • In a way WORM [wikipedia.org] would be great for forensic evidence in ensuring its permanence (beyond physical destruction).

        • Automated detection is normally considered just a screener. Consider if this were face detection - if you watch video and see somebody doing something and recognize their face, does it bother you if the automated face recognition algorithm did not identify the suspect in the same video? Would you consider it damning to have a person even watch the video, since if the suspect were there, the algorithm should have noticed everything? Not at all.
          • Automated detection is normally considered just a screener. Consider if this were face detection - if you watch video and see somebody doing something and recognize their face, does it bother you if the automated face recognition algorithm did not identify the suspect in the same video? Would you consider it damning to have a person even watch the video, since if the suspect were there, the algorithm should have noticed everything? Not at all.

            Sure, but ever heard of double-blind testing? It's how experimenters try to ensure they don't subconsciously influence the results, it's basically a per-requisite for a scientific study since the bias for the experimenter to misinterpret data in favour of a positive result is so strong.

            So imagine a recording where there are four clear shots and a fifth blip that might be a shot (partially muffled by a car), or might be something else entirely like a reflection.

            Say the algorithm says says "there's four shots

            • I do agree with that objection. If you did a lineup but the cops tipped off the witness of whom they wanted them to 'identify,' that would be a total sham. And the right way is a "blind lineup" in which the officer conducting the lineup doesn't know who is the leading suspect, for that reason.

              I do think the process came to the right conclusion by throwing out the auditory evidence entirely in this case.

        • Nothing is going to change until we start sending these dirty cops and lab technicians to prison for framing people.

          The system needs to change. There should be NO channel of communication between the technicians and cops. There should be no mechanism for requesting a "review"

          Technical evidence like gunshot triangulators, DNA analysis, etc. should never stand alone to convict anyone. It should only be used to support prosecutions when there is other evidence linking the accused to the crime.

        • A documented history of evidence tampering would make their product unusable in court. If they want to make money from their product they better start using write once read many (WORM) media- unless the police are paying them to "find the evidence".
      • by AvitarX ( 172628 )

        It seems pretty reasonable to me that someone trained can go over reports (listen to audio) and make a better determination of gun vs firework than AI. I'm not saying that's the case, but it definitely seems quite possible.

        I'm extremely skeptical of the very large distance the incident was moved though. Maybe the AI really is terrible, but how is a person supposed to do better? It seems like you'd need to do some really extreme analysis and build a detailed model of the city (which I assume the AI already h

        • The location determination is probably not using AI. It's a trivial set of simultaneous equations to compute a location of a signal when you have the time it was received by multiple receivers. Real world issues mean you need to account for multipath and clock jitter, but those are very solved problems and the uncertainty will be small for audio.

          • by AvitarX ( 172628 )

            I guess I supposed there'd be enough variation in the layout of a city over time that there's be a little bit of magic to get predictions.

            I'd expect glass vs boards vs metal window covers vs open counters for open business to have a notable effect on ground level sounds for example.

            Things like the number of cars on the street and delivery trucks and construction sites and scaffolding.

            I (obviously) don't know much about how well the environment needs to be modeled to locate sound, but to my intuition the fac

    • by XXongo ( 3986865 ) on Monday July 26, 2021 @06:23PM (#61623109) Homepage
      That's weird. The links in the article are both links back to the article.

      First link should go here https://www.vice.com/en/articl... [vice.com]
      And the second link here: https://pdfhost.io/v/RmCGSdFdT... [pdfhost.io]

    • Re: (Score:2, Troll)

      by fahrbot-bot ( 874524 )

      This what I call actual journalism.

      Can you imagine living in a world where these kind of things happen but nobody says anything publicly about it?

      If you're a (recent) Republican politician, that's basically the dream ... /sarcasm

    • Can you imagine living in a world where these kind of things happen but nobody says anything publicly about it?

      Sure, just imagine living in China, Russia, or any of a list of probably 100+ smaller countries.

      Even places like Japan that superficially have a lot of individual freedoms, but that have a 99%+ conviction rate.

      And before Cluestick the Great chimes in with the US conviction rate, remember to calculate it based on charges filed, not cases that went to trial, because in the US many cases, like the one in this very story, end up getting dismissed when problems with the evidence come up.

      • by AmiMoJo ( 196126 )

        The conviction rate in Japan is because prosecutors only proceed with cases where they are certain they will win.

        Of course there are miscarriages of justice, but more often they are that someone doesn't get prosecuted because the evidence isn't strong enough to ensure a conviction.

        The UK has a similar problem with rape, often it never goes to trial due to lack of evidence or because the victim's behaviour is judged to make getting a conviction difficult (e.g. they had consumed alcohol).

      • Sure, just imagine living in China, Russia, or any of a list of probably 100+ smaller countries.

        The USA has more people in prison than any other country in the world and yes that does include China and Russia.

    • I simply cannot imagine living in a culture where gunfire detection systems EXIST at ALL!!

      WTF USA??

      Can you not SEE and UNDERSTAND how ABERRANT this is compared to a normal 21st century western culture?

  • by quantaman ( 517394 ) on Monday July 26, 2021 @05:38PM (#61622979)

    I can see two potential scenarios here.

    First, there's some shortcoming with ShotSpotter's algorithm that occasionally need human correction. Some time sync issue, instrument error, or building reflection that needed to be manually dealt with. In that case, you better give a good solid report on how the post-processing came to that conclusion, and make it auditable by a 3rd party.

    The other scenario, the cops said "we think Williams did it and he was parked at X" and then the ShotSpotter analyst fudged the analysis to back that up. In that case someone on the ShotSpotter end should probably be looking at criminal charges.

    • by quantaman ( 517394 ) on Monday July 26, 2021 @05:47PM (#61623001)

      The summary links are broken but this looks like the original [vice.com].

      Basically, this seems to be a case of "the customer is always right", and when your customer is the police, and you don't have rigorous safeguards in place, you inevitably end up with a culture of fudging numbers to give cops the evidence they ask for.

      Something as simple as shielding analysts from the nature of the officer query would do wonders for the reliability of their product.

      • by geekmux ( 1040042 ) on Monday July 26, 2021 @06:48PM (#61623195)

        The summary links are broken but this looks like the original [vice.com].

        Basically, this seems to be a case of "the customer is always right", and when your customer is the police, and you don't have rigorous safeguards in place, you inevitably end up with a culture of fudging numbers to give cops the evidence they ask for.

        Yeah, or you could maybe, just maybe design a system like this with the fucking integrity it demands so that NO ONE has the ability to placate to any customer, other than providing the factual evidence.

        I'm reminded of several companies who refuse to hold your private keys, and purposely do not store data, in order to provide security and integrity. One would think a gunshot-auditing system that will (not maybe, WILL) be used by law enforcement and in the courtroom, would qualify for such treatment.

        Corruption demands otherwise, and there is no excuse for this.

        Put another way, imagine if a civilian or suspect modified and destroyed evidence like this? They sure as hell wouldn't be charged with the non-crime of "post-processing".

        • Yeah, or you could maybe, just maybe design a system like this with the fucking integrity it demands so that NO ONE has the ability to placate to any customer, other than providing the factual evidence.

          Any kind automated classification system needs the ability for a human to override. Like fraud detection at a bank, if a customer calls in and says a transaction is or isn't fraud, that overrules everything.

          I don't see why this company shouldn't be doing the same, if they know X shots were fired at Y location, and it was classified as a lawnmower backfire on the other side of the street, update the incident manually, obviously create an audit trail, and eventually feed that data back into the classificatio

          • Yeah, or you could maybe, just maybe design a system like this with the fucking integrity it demands so that NO ONE has the ability to placate to any customer, other than providing the factual evidence.

            Any kind automated classification system needs the ability for a human to override. Like fraud detection at a bank, if a customer calls in and says a transaction is or isn't fraud, that overrules everything.

            Correcting a classification (gunshot vs. firecracker) is one thing. Purposely manipulating automated results and evidence of location in order to align with a "target of opportunity" (suspect), is another matter entirely.

            Let's put it this way; if their actions were integral here, then perhaps you can explain why prosecutors chose to withdraw ALL evidence created by this system, rather than defend their product and "override" actions taken, against a public defender.

            The product may work. The implementatio

            • by Cederic ( 9623 )

              The public defender should re-introduce the evidence, as it seems to me it demonstrates that gunshots were not fired at that location at that time.

          • Any kind automated classification system needs the ability for a human to override. Like fraud detection at a bank, if a customer calls in and says a transaction is or isn't fraud, that overrules everything.

            We have that ability. It is called a court with a judge and a jury.

        • Yeah, or you could maybe, just maybe design a system like this with the fucking integrity it demands so that NO ONE has the ability to placate to any customer, other than providing the factual evidence.

          ... and then you go bankrupt because the main consumer of this information is looking for the product they are demanding, and not particularly interested in funding your dedication to integrity.

          • Yeah, or you could maybe, just maybe design a system like this with the fucking integrity it demands so that NO ONE has the ability to placate to any customer, other than providing the factual evidence.

            ... and then you go bankrupt because the main consumer of this information is looking for the product they are demanding, and not particularly interested in funding your dedication to integrity.

            Yeah, and in this case, that highly-specialized expensive software, along with all of the criminal-busting "evidence" it "provided", this was the end result:

            "...the prosecutors withdrew all ShotSpotter evidence against Williams."

            And now that every lawyer knows just how shitty that solution has become because of what corruption is "demanding", we'll see who goes bankrupt. Wouldn't be surprised if every court case involving this tech gets re-opened and re-examined after this. Seems kind of pointless to pay millions for a solution to not use it. Of course, that's just another e

            • And now that every lawyer knows just how shitty that solution has become because of what corruption is "demanding", we'll see who goes bankrupt.

              Good luck on that.

              First, evidence for prosecution is far from the sole use for this tech. Even if this ceased to be used for that purpose entirely, it's purported use for tracking down gunshots, or even other noises, for purely investigative purposes would likely keep it in use. These uses are difficult to quantify, and once a city government has bought into the marketing hype they'll be real slow to accept, and even slower to admit, they may have made a mistake.

              Second, and more important, providing

    • I worked on time difference of arrival sound localization in school, in my program through hyperboloid positioning like GPS, I dont know what they use. Anyway in what I used there was an 'uncertainty principle' type thing where the more certainty you have to direction, the less you have of distance of the sound. So if the sound was far very away from cluster of sensors it could be that off. Also, you have to solve the correspondence problem between all mic inputs, finding the same origin sound in each which

  • Nice frameup (Score:4, Interesting)

    by Revek ( 133289 ) on Monday July 26, 2021 @05:48PM (#61623003)
    Too bad there is no longer any punishment for manufacturing evidence.
  • I want the source code in court and if there is an NDA you must acquit

    • Frankly, we don't need the source code. Raw audio files with timestamps would be sufficient to re-create using our own math. I would argue that this should be public information regardless of who the vendor is (shot spotter) in this case... since it was produced at the behest and at the expense of a government entity.

      • I agree but Isn't the locations of the microphones secret (to avoid sabotage)? That would be needed to do any calculations.
        • If they release raw audio files with timecodes then the locations of the microphones won't remain secret for long. Reverse triangulation from the locations of the shots will see to that after just a few cases.

  • This definitely needs explaining, but it sounds an awful lot like the defense is trying to pull the defense 'well, this automated mechanism must be better than the humans and since it didn't conclude in support of the prosecution, it must be a frame up' which isn't that strong an argument. We all know how piss poor automated systems can be at times at getting things right, so automatically assuming they are superior, or that the human interpretation is a frame up just doesn't hold much water. Let the expe
    • by suutar ( 1860506 ) on Monday July 26, 2021 @06:03PM (#61623055)

      The fact that the prosecution would rather pull the evidence than try to back it up does not instill confidence.

      • We don't know if they can back it up yet as it hasn't gotten to court yet. This whole thing is about the defense trying to get it excluded from the case.
        • We don't know if they can back it up yet as it hasn't gotten to court yet. This whole thing is about the defense trying to get it excluded from the case.

          Actually we do know, they won't back it up in court because they chose not to.

          It started with the defense trying to get it excluded from the case.

          It ended with the prosecution withdrawing the evidence rather than defend it in court.

          IANAL but it sounds like the prosecution and/or ShotSpotter doesn't find the evidence defensible or their methods don't stand up to scientific rigour. Sure, they probably have some legitimate worries about their IP entering the court record... but if you want to supply forensic e

          • If that is the case, then definitely. If they won't stand behind their interpretations, their interpretations are utter garbage, at least legally.
        • by XXongo ( 3986865 )

          We don't know if they can back it up yet as it hasn't gotten to court yet.

          And it won't go to court. When the evidence was challenged, the prosecution removed it from the case.

          This whole thing is about the defense trying to get it excluded from the case.

          Not the defense. The prosecution.

          Because they were afraid that if the evidence got challenged, they would lose this, and other cases.

          The link in the article is broken, but the objections to the SpotShot results are here: https://pdfhost.io/v/RmCGSdFdT... [pdfhost.io]

          • Not the defense. The prosecution.

            Because they were afraid that if the evidence got challenged, they would lose this, and other cases.

            No, the defense filed a motion to get the evidence excluded, and rather than defend against the motion, the prosecution withdrew the evidence. It very much *did* get challenged, that is what started this.

      • by _xeno_ ( 155264 )

        As I understand it, ShotSpotter is not intended to be used for evidence. It's supposed to be an early warning system, alerting police that a shooting has happened that they should investigate.

        Taken in that light, what happens makes perfect sense: ShotSpotter heard a sound, identified it as a firecracker, and determined its likely location based on that. A small firecracker is a good bit softer than a gun, so it likely decided it was closer based on that. (This highly depends on the exact firecracker and exa

        • Clearly they are not pinpointing the location with a single microphone so the volume of the sound does not matter, only the time difference between the various microphones that picked it up.
        • Later, the police determined that the time of the detection matched a known shooting at a different location with a different weapon, and informed ShotSpotter, so they could update their algorithm.

          That's bull. If the intent is to improve the algorithm, you would not update the records in place. Instead, you would have other fields in the database for actual locations, leaving the predicted locations unchanged.

          Unless that's what happened and the police are misrepresenting the data.

          In reality, there should b

        • Accoustic shot tracking works by timing the sound from different locations to trilaterate the location. The volume of the sound is irrelevant, just the speed of sound (changes with humidity and air pressure). Sound waves bounce off buildings, giving a longer flight time that gives incorrect distances. Sound is often blocked by buildings, meaning some shots won't be heard (especially if the shot was fired inside a building or car).
    • No, this is about the prosecution and the police trying to rewrite irrelevant data to produce evidence to make their case. I said "produce", not "enhance" because they had the option of ignoring sounds the system identified as coming from a completely different location. This isn't even a matter of hiding exculpatory evidence- it wasn't even connected to the case at all. Fiction is not evidence. Period.
      • Then the defense should be able to quite easily produce an expert to refute the interpretation of the data.
        • That's EXACTLY what the defense requested, but the prosecution pulled the data from the case before the defense could look at it. It's no longer evidence in the trial because the prosecution didn't want an expert to look at it.

  • Maybe it's time to start muddying the waters a little. I wonder if nasty, evil people with decent sound systems could play recordings of gunshots throughout the city at random times, and maybe muddy the data pool a bit.

  • We just learned there is a system that records loud noises, classifies them (I hope reasonably well) as gunshots or fireworks or whatever, determines their position (I hope reasonably well), and employees running it can alter this information. "We need a gunshot at location X", "No problem, there was an exhaust blowing at location Y, we just change that".

    If that is what can happen, then basically nothing from that company can be trusted. Ever.
  • even if he didn't do it.

Make sure your code does nothing gracefully.

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