Little is known of the convict Dave Sykes who would become known to Metropolis at large as "John Doe". Having served 22 years of a life sentence, on supposedly trumped up charges, John Doe escaped from the Stryker's Island Maximum Internment Center. Outfitted, by the Monitor, with a series of high tech weapons, John Doe sets out to settle a decades old score with the Metropolis justice system. His first target is the police precinct that he was taken to, when he was first arrested. Utilizing a high intensity vibration device, cast in the shape of police issue handcuffs, John Doe, from on high, began to shake the precinct building, down to it's very foundations. The vibratory shocks are intense enough to give even Superman pause, when the hero arrived on the scene to stop John Doe. To further keep Superman occupied until he could finish razing the police precinct, John Doe dropped explosive charges down on the panicked crowds below, forcing Superman to make a choice between saving the people or the structure. In the time it takes Superman to rescue the endangered civilians, John Doe was able to completely demolish the police precinct. Superman moved in to apprehend John Doe, but suddenly lost his ability to fly. Grounded, Superman could do nothing to stop John Doe from escaping.
After his initial encounter with Superman, John Doe asked the Monitor to upgrade his weapon's tech. He then set about taking down his second target, the Metropolis courthouse. Superman was quick to re-engage John Doe, as the courthouse began to come down. Steeled for John Doe's vibratory blasters, Superman would probably have apprehended the masked convict, had he not suddenly suffered a crippling bout of terror, at the thought of being mortally injured in the melee. Superman was able to regain his nerve long enough to sever John Doe's weaponized handcuffs, forcing John Doe to abandon his goal of destroying the courthouse, that night. Superman again allowed John Doe to escape, this time due to his belief that it was not his job to bring John Doe to justice.
Once John Doe was able to repair his primary weapon, he struck at his final target, the prison that "stole" the last 22 years of John Doe's life. Superman, however, had by this time figured out John Doe's motives, and anticipated John Doe's appearance at the prison. Using his super-strength, Superman crushed John Doe's handcuffs, and turned him over to the prison authorities. Throughout all three of Superman's encounters with John Doe, the Man of Steel had suffered momentary memory lapses, all of which had been beneficial to John Doe. John Doe, in fact, boasted of being the cause for Superman's sudden bouts of selective amnesia. When questioned about it, John Doe refused to give up any information to Superman. In truth, John Doe was in no way responsible for Superman's memory losses. A completely separate event had afflicted Superman, the timing of which allowed John Doe to accomplish more of his goals then he probably would have, had he not been facing a compromised Man of Steel.
While the circumstances of John Doe's arrest and eventual incarceration have never been revealed, his musings indicate that he was convicted of killing four men. Though John Doe contends that it was self defense. His savage attack on the three municipal buildings, coupled with his callous disregard for the lives of Metropolis's citizens, seem fair indicators of a deranged criminal mindset, all but validating the court's opinion of John Doe as a cold-blooded killer. It is unknown, however, how big a part John Doe's decades long incarceration played in his violent maliciousness. It is telling that he chose the code name, "John Doe". He considered himself to be a forgotten, faceless name and number, trapped forever in a broken down, obsolete system. His featureless mask and weaponized handcuffs served to symbolize how John Doe saw himself, possibly suggesting that the man he had been was broken down considerably in prison, leaving only the revenge driven "John Doe" in that man's place.