Like other deeds, a quitclaim deed conveys title from a "grantor" or owner to a "grantee." Unlike other deeds, a grantor has no legal liability if the title is flawed in some way. Conveying title with a forged or fraudulent deed, however, is a felony. If found guilty, the forger will suffer whatever penalty your state mandates for the crime.
Missouri and Florida Cases
In Kansas City, Missouri, a series of thefts in 2004 involved criminals forging homeowners' signatures on quitclaim deeds, then filing the deeds with the county. The thieves could then resell the property or take out a home equity loan using the house as collateral. In some 2008 forgery cases in Florida, the thief not only faked the owner's name but that of two witnesses, plus authorizing the document with a fake notary seal. The favorite targets are out-of-state or elderly owners who won't suspect a problem until it's too late.
Penalties
Quitclaim deed forgery, in many states, may constitute multiple crimes. In California, for example, you commit a felony the moment you forge a property owner's signature on a quitclaim deed. If you then file, register or record the deed, that's another crime. The forgery could earn you three years in prison and a $10,000 fine for each fraudulent deed. Filing the deed could result in a $75,000 fine on top of that. The judge can add on several years more, depending on how much money the homeowner lost because of your crime.
Defenses
Just because someone's accused of forgery doesn't mean he'll be convicted. For example, the accused could show that he didn't forge the deed; instead, the forger impersonated him and used his name as the grantee to conceal his true identity. In California, it's a legal defense to show that the rightful grantor approved of what you did: She wanted to give you the house, for instance, and told you to go ahead and sign her name.
Considerations
A forged deed is completely invalid: Once the forgery is discovered, the title transfer is null and void. If the forger conveyed title to someone else, that transfer is invalid, too, as are all subsequent conveyances, even if some of the buyers were innocent and unaware of the fraud. If the thief used fraud to trick the grantor into signing the deed, the thief has no right to the property, but if he sells it to a legitimate buyer, that sale might hold up.