Borrowed Biometric Bypass

"Kryten: Logically, sir, there is only one way you could possibly have opened that door. I feel quite nauseous. -- Where is it? Lister: Where's what? Kryten (horrified): Oh, sir, you've got it in your jacket! Lister: I got us out of the hold, didn't I? Kryten: Sir, you are sick! You are a sick, sick person! How can you possibly even conceive of such an idea? Lister: Hey, cheer up... or I'll beat you to death with the wet end. Kryten: Sir, if mechanoids could barf, I'd be onto my fifth bag by now..."

- Red Dwarf, "The Inquisitor"

Once upon a time, infiltrating a base was pretty easy: just knock the guards out, take the keys, and get in. Fortunately, modern high-tech facilities, or in The Future have more cunning devices, and can identify the guards by unique biological features, such as handprints or retinal scans. These cunning devices are reliable, efficient, and not prone to believing just anyone who happens to be wearing the right uniform. Great, huh?

Unfortunately, the more dangerous individual won't need to get your guards to agree: He'll find someone with the right access, and engage in some very unpleasant surgery. He may remove a guard's eye, or he may simply lop off his or her head and hand with a big ol' sword. Then equipped with those body parts, he'll simply apply these to the biometric authentication device in question, and get through.

This raises the question of whether or not any such devices would be able to tell whether the hand or eye in question was attached to a living body. In reality, this actually is a key consideration in designing biometric security. Some devices (the cheaper ones, mostly) ARE vulnerable to this kind of thing. Needless to say, such a weakness is considered an absolute disqualification for usage in any classified government facility.

This is rarely used by good guys, as it's definitely on the morally dubious side of things, even if you don't kill the victim. A more moral person may have to talk or threaten the guard into showing his Eye-D, or simply wrestle the poor Mooks into place.

Note that this is not about bypassing biometric scanners in in general. This is about the bloody way to get around them.

Comic Books

 * The Joker once gained access to a government vault by Joker toxin-ing the guards and dragging one over to a biometric scanner. The vault, incidentally, held Doomsday.
 * Used by fellow Arkham inmate Jane Doe in an attempt to escape through an emergency exit requiring a fingerprint scan, retinal scan, and voice ID. As Jane's modus operandi is wearing the skin of the people she kills and taking over their identities, she was well prepared, bringing her latest victim's severed hand and preserved eye, plus a recording of the victim pleading for her life.
 * In a Weird Worlds story, when an elevator Lobo's hijacked reaches his destination, the doors won't open. The elevator attendant explains that they're tied to his DNA, the sensor for which is several floors up, where they just came from, but the elevator won't go back up because he didn't have the chance to use the sensor when Lobo got on. Since there's no ceiling between them and the sensor, Lobo just blows the attendant's brains out, splattering his blood on the sensor.

Film

 * Used in Shoot Em Up to use a disabled gun which required a thumbprint.
 * Simon Phoenix in Demolition Man gets through a door locked with a retina scanner by removing the authorized man's eye. Surprisingly having a pen jammed into it (to hold it with) doesn't seem to obscure the retina at all.
 * Might have been an iris scanner, of course.
 * Except the door says "retina coding accepted"
 * John Spartan also mentions that Phoenix can't mug anyone for money "...unless he rips off somebody's hand, and let's hope he doesn't figure that one out."
 * In Spaceballs, Lone Starr knocks out a guard and uses his hand to get into the self-destruct device chamber.
 * In Die Another Day, James Bond and Jinx get past a hand scanner by severing the arm of a recently killed henchman and pressing it against the scanner.
 * In Never Say Never Again, the remake of Thunderball (both starring Sean Connery as Bond), a bad guy had an eye transplant to get past a retinal scanner protecting some nuclear weapons.
 * In Double Team Jean-Claude Van Damme cuts out the skin of his own thumb to provide time-needed biometrics while he is elsewhere.
 * Subverted in District 9. Since the alien weaponry can only be used by an alien hand, various attempts are made to use severed arms to fire the guns. That doesn't work, though, since the arms need to be alive.
 * In The Film of the Book of The Dead Zone, John Smith has a vision of Gregory Stillson as president. Stillson is hot to launch a nuclear strike at the Soviet Union, but to activate the Nuclear Football, he needs a general's handprint-scan in addition to his own. Stillson tells the general, "Put your hand on that pad or I'll cut it off and do it myself!"
 * Used by one of Arnold Schwarzenegger's characters in The 6th Day. He cuts off the thumb of a character (along with some other things) and then uses it to both start up a truck, and get into high security areas in the library cloning facility.
 * In Back to The Future Part II we see a brief glimpse of a news article in 2015 that says "Thumb Bandits Strike Again". Since all monetary transactions in that future are done by thumb scanners, criminals would start to steal victims' thumbs.
 * In Doomsday, a dying infected man armed with an axe uses this method to break into the building sheltering.
 * In Minority Report, the protagonist's wife used his eye to enter the . This invokes a Fridge Logic issue as of why his eyes have not been revoked access.
 * A healthy trade for blood samples, urine samples, fingerprints, dandruff, and hair existed in the movie Gattaca. The protagonist used this to break a glass ceiling fake the identity of another man, but presumably others used the black market in biologicals for more nefarious purposes.
 * In both the book and the film of Angels & Demons, a CERN scientist's eye is cut out to fool a retina scanner.
 * In Doom The Movie, Sarge takes the severed arm of a dead scientist and places the palm on an access scanner to obtain the BFG.
 * A robotic version appeared in Futureworld, the sequel to Westworld. A door has a device that scans the retinas of anyone trying to get in. To pass, you must have a pattern that only robots possess. The Heroes deactivate a robot and rip off its face, then use the face (and its eyes) to fool the device.
 * Ultraviolet has a system to scan someone entering a secure facility to make sure they aren't vampires. It involves two thick needles stabbing the subject in the wrists. Getting around it by temporarily altering one's blood seems fairly simple.
 * In National Treasure, Gates uses Chase's thumbprint he acquired to infiltrate the vault storing the Declaration of Independence.
 * In The Avengers, Loki and his minions use a fancy piece of stolen S.H.I.E.L.D. tech that lets them scan someone's eye and turn it into a hologram good enough to fool a retina scanner. Loki probably didn't have to jam it right into the poor man's eye socket tho...

Literature
"Oar: That is foolish. If criminals wished to impersonate you, they could simply cut off your hand. Then they could rub the detached member against the wall-- Uclod: Whoa! Just whoa. What is wrong with you, missy? How can such grisly ideas pop into such a pretty head? Oar: I am simply practical. Unlike your Zarett's security precautions, which would seem to encourage villains to amputate-- Uclod: Hush! Right now. Not a word."
 * Used in one of the Artemis Fowl books, although they later reattach the finger via magic.
 * In a later book, the fairies have one that is specifically designed to detect a pulse in order to prevent this (justified due to the fact that it was designed by Foaly).
 * In the Dan Brown novel Angels & Demons, physicist Leonardo Vetra gets his eye cut out to get past a retinal scan.
 * In the first Schaeffer's Last Chancers book, the team has to bypass a palm scanner that can detect whether the hand still has a pulse running through it. They circumvent it by removing the hand an authorized officer, then surgically attaching it to one of the team member's wrists, via some tubes so he can hide it in his pocket.
 * Something similar in Lois McMaster Bujold's Mirror Dance, although here's it's a code-key embedded in a ring, not a biometric. Sounds squick-free? No, because the ring in question is apparently riveted to the owner's finger bone and quite impossible to remove...
 * And to get past the lock requires both the ring, and a palm print.
 * One of the Halo novels had a finger scanner...which releases a blood-drawing needle during the scanning.
 * In one of the Women of the Otherworld books, the doors of the top secret facilities are unlocked by fingerprint readers embedded in the door knobs. Our hero ambushes a guard and applies the logical solution to their problem.
 * Discussed in Ascending. Uclod demonstrates his Living Ship's security features to Oar, including the fact that it won't operate until confirming his DNA, palmprint, and fingerprints. Oar is unimpressed:


 * In Robots and Empire, two villains disagree on how best to perform their mission. One has a gun. The other's thumb is needed to work the required equipment. The armed one states that if he'll blow off the other's head off, the thumb will be quite intact.
 * In Sergey Lukyanenko's A Lord From Planet Earth amongst one of the Precursors' artefacts there are little one-time use devices capable of making planets barren wastelands. However, they need to be activated by a human hand. Attached to a living human being capable of reasoning its activation. Yes they tried other options, including a severed warm human hand.
 * Rebel Force: Trapped has Luke Skywalker going through an Imperial base with a stolen passcard just fine until he reaches a palm scanner. Fortunately, it was guarded by the only two stormtroopers he'd encountered in the base who were inclined to shoot first, so he could kill them and use one's hand without violating his Martial Pacifist preferences.
 * In Kim Newman's Dark Future novel Krokodil Tears,'' via a severed hand, this is how Jessamyn bypasses the security system locking down Bronson Manolo's DeLorean in Dead Rat.

Live Action TV
"Gan: Look, we just need the hand. If you want to stay attached to it (grins), do as you're told."
 * In one of the Lexx movies, Giggerota ripped off Stan's hand so she could pilot Lexx without him. The former Shadow brains provided the voice.
 * In Red Dwarf (Inquisitor), Lister and Kryten get replaced by another Lister and Kryten, who subsequently get killed (and blown up). Lister uses other-Lister's severed hand to open a door, leading to the exchange quoted above.
 * In Dark Angel, a man got both his eye gouged out and his hand cut off (at two different occasions by the same guy) so that the maiming guy could get into two different high security installations after he had gone rogue from the evil corporation he used to work for.
 * Torchwood, "End of Days" with Capt. Jack. He's not killed for it but it's revealed after Owen kills him that they need his retinal scan to okay the use of the Rift Manipulator, so they hold his corpse up to the scanner. Like always, Jack gets better.
 * In Torchwood: Miracle Day, Jack and Gwen use non-invasive methods to get the biometric data from their target... the assassin chasing them, however, is a little more pressed for time. Bonus points for needing . The tissue in question is immortal and thus still counts as alive, ripped off or not.
 * The MythBusters tested biometric fingerprint scanners, including a top of the line model which was supposed to read body temperature, salinity, and electrical current, but they all proved very easy to fool.
 * To wit: One of them was fooled by a black and white computer printout of the finger in question (that had been licked to cover salinity).
 * They also found that the expensive reader sold to be used as a door lock, was easier to fool than the cheap one used as a log-in device on a laptop.
 * The Global Frequency pilot inverts the usual crisis - while storming a secret prison, Miranda Zero is completely prepared to get past the retinal scanner, but runs into trouble when it turns out to be a password-protected scanner.
 * Threat Matrix has a related example where Israeli agent attempts to frame a Palestinian agent for a hit by wearing the dead man's fingers.
 * Threatened by the heroes (well, sort of heroes) so they could escape the cells of a prison ship in the second episode of Blakes Seven.

"Data: I assume your hand print will open this door, whether you are conscious or not."
 * In another episode, Vila got round a scanner by doing the lifting fingerprints trick.
 * Kessler (a 1981 spin-off of Secret Army) has the title character informing his fellow war criminals in South America that they can't access his Swiss bank accounts by cutting off his hand, as the system only works with a living hand.
 * Alias: During Marshall's All Up to You story, he accidentally shoots a foe while attempting to furtively assemble a Scaramanga Special. With the enemy dead and unable to be bluffed into allowing him past, he has no choice but to remove his eyes, coached by Jack. The first attempt, with a knife, doesn't go so well, but then he finds a spork, which works better.
 * In a Star Trek: The Next Generation episode, a genetically engineered Super Soldier got around the fact that the commbadges were keyed to fingerprints by knocking out a guard and using his finger to activate it.
 * In a different episode, a time traveler from the past with a stolen time machine from the future (got that?) tries to kidnap Data. Since his handprint is required to open the door, nobody has been able to get into or to even scan the inside of the craft. Once the time traveler learns that he can't incapacitate Data (due to his stolen phaser being disabled), Data subtly but effectively convinces him to give himself up...

""Give this to Dr. Gilligan." "What is it?" "(smiling) He'll recognize it.""
 * In the Star Trek: Deep Space Nine episode "Who Mourns for Morn?" a criminal from the Orion Syndicate threatens to do this to Quark, needing his thumb to sign for delivery of a package. His brother points out that they can't very well expect to be taken seriously if they use a severed thumb to sign the invoice.
 * In Jekyll, Hyde is obviously a bit gleeful about this one—to the point where he puts the victim's severed thumb in a lunch box and abruptly presents it to a passing scientist:


 * The husband of Ilsa Pucci from Human Target was killed for his eye, so his lawyer could get into a biometrically-sealed vault to steal his identity.
 * Averted in the fourth season of Burn Notice, but only because Larry doesn't have a bonesaw with which to remove the dead Brennen's left hand, a fact he laments.
 * The paintball game show Crossfire had one "mission" to steal a handily tanked "eyeball" to use on the enemy base biometric scanners. Since on at least one occasion the entire team were wiped on that mission, the host had a tank with his gran's eyeball in - "because who could refuse a little old lady access?"

Tabletop RPG

 * Shadowrun. This is noted in The Neo-Anarchists' Guide to Real Life as a way to fool biometric security devices (such as doors and credsticks). Unfortunately the devices' designers have figured this out and altered the devices to check and see if the body part being used is still alive and attached to a body.

Video Games

 * Dead Space 2 makes you use whole bodies... or at least chunks of them.
 * Subverted Trope in Metal Gear Solid 2: Sons of Liberty: it's stated up front that the retinal scans can't detect dead eyes, so the player has to drag the struggling guard to the scanner.
 * Used in a more comprehensive way with the "nuclear football" that the president must have access to to activate a nuclear weapon. Inside the briefcase is a complex device that constantly monitors the president's, well, everything, so if he dies or is in an altered state of consciousness, no nukes can be activated.
 * Played straight in Metal Gear Solid 4: Guns of the Patriots, Old Snake had to take a dead soldier's gun. Since the gun only reacts to the soldier's nanomachines, Snake had to bleed the soldier's out over the gun so he can use it.
 * Likewise in Splinter Cell, though you need a breathing, conscious person for the retinal scanner, as the scanners can tell if they're living or dead.
 * Used straight in Fallout 2 in an abandoned Military Base. Retinal scanners operating locks in various sections of the base require specific eyes to unlock.
 * Averted in Predator: Concrete Jungle, where scanners require a scientist to unlock. It's unknown if the predator could just rip off the heads since he is strong enough to simply drag them to the scanners and ram them in hard enough to kill them while opening the door.
 * But played straight in the 2010 ''Alien vs. Predator game where the Predator has to use a severed head to open several doors with retinal scanner locks.
 * Used in the original System Shock, where you can use the entire head of an (already-dead) officer onboard the ship to reach an optional area.
 * Used in the remake of Alone in the Dark in the museum, where you need to use a sword to hack off a guard's arm to get past a scanner. It's all right, he's already dead.
 * Quite gruesomely done in Resident Evil 4 where after defeating Mendez in his plaga form his false eye pops out, whereupon Leon scoops it up and puts it in the scanner. If you examine the glass eye (probably because you're wondering why in the heck a retinal scanner can read it), you learn that the glass eye had an encryption on the outside, which is what the scanner reads.
 * The combination of glass eye and retinal scanner also pops up in The Longest Journey.
 * Shadow Man has a variation on this in the prison level. It's actually a keycard scanner, but the card in question is being held in a death grip and can't be removed without taking the hand.
 * Buffy the Vampire Slayer: Chaos Bleeds requires you to pick up a severed hand to use on a fingerprint scanner and later on a severed head for a retinal scanner.
 * Used in Prey, with a severed alien hand which even gets progressively mankier throughout the game.
 * In D|WARP Software's Enemy Zero, one of the items Laura Lewis collects is a hacked-off pair of fingers, which she uses to bypass a DNA scanner. Stay classy, WARP.
 * The 2005 FPS Area 51 had one puzzle be solved by picking up the severed hand to a guard and placing it on a scanner while you hit the other one. Later, you had to pick up a severed head to get through a retinal scanner.
 * This is a solution to get to the shuttle bay and steal a shuttle in Space Quest 6: The Spinal Frontier. The shuttle bay entrance is guarded by two security guards, who won't let Roger inside. After knocking them out, Roger realizes that both buttons have to be pushed simultaneously in order to open the doors. He goes to the ship's android Lieutenant Commander Circuit Sidney and asks to borrow his arm. After using his own arm and Sidney's to open the door, he realizes that the shuttle can only be started by an authorized crewmember, which Roger (despite being an Almighty Janitor) isn't. He goes back to Sidney and asks for one of his eyes (why a senior officer would give his body parts to a janitor without explanation is not explained), which he uses to fool the shuttle's retinal scanner.
 * Quake II has a locked door, with the item required to open it being a Commander's Head.
 * Xenogears has an even more cold-blooded example: It's kind of hard to call this Kick the Dog, since this character can't walk two feet without punting a puppy. But that doesn't mean it's not incredibly satisfying to beat the shit out of him in the Boss Battle.
 * In Penumbra: Black Plague you get past several security scanners like this, using blood to enter the kitchen, then a hand and head to enter the library. Interestingly, one door that leads to the cryogenic freezer has a hand scanner that when you try to scan the hand you have already procured at this point, tells you that the person whom this hand belongs to is in critical condition and will not accept it.

Web Comics

 * Used in Chopping Block here
 * Done twice in SSDD, and kind of an Ironic Echo when you consider the second one was chronologically before the first.
 * Suggested, though not actually used in Schlock Mercenary during the CSI parody arc.
 * The Adventures of Dr. McNinja: "Allow me to perform a simple amputation, and I'll be right back." Subverted in that the dinos have figured that trick out. So they have to do something different.

Western Animation

 * Unusual example in Sherlock Holmes in the 22nd Century, rather than cutting them off, the thieves cloned thumbs and eyes to fool scanners.

Real Life

 * According to this article in most US jurisdictions it is not legally clear if cops can do this with phones, and the article advises peaceful protestors to disable biometric login and enable pin login (and gives advice on how to do this).