Despondent at his fall from grace, he went to visit architect David Madson in Minneapolis, where he had moved, and discovered that he had become acquainted with Jeffrey Trail, who had left the Navy and coincidentally also migrated to the same city.
Cunanan was reportedly jealous of the professional and financial success of both of his previous lovers, in stark relief to his own circumstances, and became obsessed with the belief that they were having an affair behind his back.
This jealousy increased over the following months, despite their denials until, on 26 April 1997, Cunanan returned to Minneapolis determined to get the truth. Despite warnings from mutual friends about Cunanan’s state of mental health, Madson did not appear to have taken this seriously and he arranged for Trail to visit his apartment the next evening, so that they could both address Cunanan’s suspicions head-on.
This proved a disastrous plan. Cunanan and Trail had a heated argument that quickly became violent, with Cunanan taking a kitchen hammer and bludgeoning Trail to death in front of the terrified Madson. They rolled his bloody corpse into a Persian rug, and made good a plan of escape. Why Madson agreed to assist Cunanan after the attack remains a mystery but, when concerned work colleagues reported that Madson had disappeared, an investigation of his apartment revealed Trail’s dead body and the two were forced to flee the city in Madson’s Jeep.
Police discovered evidence at Madson’s apartment that immediately identified Cunanan as the killer but had no idea where the two had disappeared. On 29 April 1997, Madson’s body was discovered 45 miles north of Minneapolis, he had been shot three times. It became clear to the police that Cunanan had struck again.
Cunanan’s next victim was a 72-year-old Chicago real estate mogul, Lee Miglin, who had the misfortune to be in the wrong place at the wrong time. On 3 May 1997 Cunanan gained access to Miglin's home, where he tied up Miglin and subjected him to horrific torture which included punching, kicking and stabbing with garden shears, before finally sawing open Miglin’s throat with a small hacksaw. Following this brutal attack, Cunanan stole personal items from the house, including some gold coins, and made off in Miglin’s Lexus.
This third death was also linked to Cunanan, who made no effort to conceal his tracks, and the FBI was alerted, quickly launching a countrywide manhunt. Although initially able to track his movements through his use of the in-car telephone in the Lexus, Cunanan’s trail went cold when he ditched the phone and began looking for a replacement vehicle.
By this time, he had travelled to Pennsville, New Jersey where the caretaker of the local cemetery, 45-year-old William Reese, was Cunanan’s next victim of convenience. On 9 May 1997, Reese was shot dead for the keys to his red pickup truck.
Cunanan then drove down to Miami, Florida in Reese’s stolen truck, where he arrived the next day. He took a long-term room rental in a beachfront hotel that had seen better days, intending to settle in Miami. Cunanan  was initially careful of frequenting the gay nightlife of Miami, as police were still conducting a nationwide search. However, as time passed, he grew bolder in his behaviour, using his well honed 'chameleon' skills to blend in with the locals.
Despite three appearances on America’s Most Wanted, the nationwide hunt for Cunanan showed little progress. The killer’s lack of care about covering his trail was counter-balanced by the incompetence of the police forces hunting him, who wasted a number of opportunities to bring him to justice. In one instance he was recognised in a Miami shop but was allowed to leave unhindered while a shop assistant went to alert the police. On another occasion, he pawned the gold coins stolen from Miglin, which required him to produce identification for security reasons, which he did. This was sent to the local police, in accordance with regulations designed to identify wanted felons, but the information was never followed up and the connection was never made.
It is not known whether Cunanan travelled to Miami specifically to seek out Versace or whether his selection as a target arose out of the fashion guru’s almost mystical status amongst the inhabitants of South Beach. Within a few weeks Cunanan had selected his target and made plans to establish an encounter with Versace, staking out the areas around Versace’s South Beach villa where the designer went to relax. The conjecture was that Cunanan selected Versace as the epitome of success and glamour to which he had always aspired, alternately that Versace symbolised the wealthy elder men who had let Cunanan down, forcing him into his current predicament.
Whatever the reason, on the morning of 15 July 1997, Cunanan walked up to Versace on the steps of his Miami home, where he had just returned from his regular morning coffee, and fired two shots into the back of the designer’s head.