Andrew Phillip Cunanan, born 31 August, 1969 to parents Modesto and Mary Ann Cunanan, grew up in an upper class suburb of San Diego, California. While growing up, Cunanan was known for his keen intellect and large craving for attention. In 1988, while Cunanan was attending the University of California, San Diego, his father was accused of scamming money out of his clients through his business as a stockbroker and fled to the Philippines. Cunanan dropped out of college and joined his father but soon returned to the US.

A few years later, Cunanan was living a life of luxury through the earnings of whichever wealthy, older boyfriend he was with at the time, sometimes under different names. His life continued in this manner until late 1996, when Cunanan uncharacteristically began to let his physical appearance worsen and complained to acquaintances of his loneliness. In April of 1997, Cunanan told his friends that he was moving to San Francisco, California. It's likely it was at this point that Cunanan discovered he was HIV-positive and his unusual depressing behavoir was a result of this discovery.

On 25 April, however, Cunanan flew from San Diego not to San Francisco but Minneapolis, Minnesota, where he met up with former lover David Madson. Two days later, Cunanan invited Jeffrey Trail, a friend (or more, according to some) of Madson's, to Madson's home. Neighbours reported hearing intense shouting that night and, days later, Trail's body was discovered within the house rolled up in a carpet. On 1 May, 1997, Cunanan drove to a lake north of Minneapolis with David Madson and shot him to death with a .40-caliber pistol that had belonged to Trail.

Fleeing the area in Madson's Jeep, Cunanan headed for Chicago where he tortured and killed real estate broker Lee Miglin (Cunanan wrapped Miglin's head in duct tape and cut him until finally finishing him off). It's still unknown what exactly Cunanan's relationship to Miglin was, if anything beyond possibly knowing of him through his financial success. It's possible Miglin was targetted solely for the purpose of obtaining money, though the fact that Cunanan tortured him and not the victims he had a more personal involvement with indicates their might be more of a connection between the two. Cunanan took cash and a Lexus from the slain Miglin and fled eastward. On 9 May, Cunanan shot a cemetary worker named William Reese to death in Pennsville, New Jersey and took his pickup truck down to Florida. Once again, no known connection between Cunanan and his victim.

On 12 May, Cunanan checked into the Normandy Plaza in Miami Beach. For the next several weeks he apparently didn't kill anyone, living off money taken from Lee Miglin presumably. On 14 July, 1997, however, Cunanan shot the wealthy and famous fashion designer, Gianni Versace, to death at the entrance to Versace's mansion. Police found Cunanan's passport and some bloody clothes within the stolen pickup shortly thereafter in a parking garage near Versace's residence. After this evidence was discovered (and put together with other evidence from his previous murders that pointed to him), Cunanan became a well-known and oft-discussed topic in the American media and (mostly false) sightings of him were reported all over the country. Rumours circulated that Cunanan was a master of disguise, able to pass himself off as someone else, even as a woman. The real reason Cunanan was so hard to find, it seems, wasn't due to any cunning diguises or charm but a surprising level of incompetence on the part of several law enforcement agencies. Cunanan, already on the FBI's most wanted list in connection to the other murders prior to the Versace slaying, was able to not only rent his room at the Normandy Plaza in his own name but pawn a ring stolen from Miglin, giving his name, address at the hotel, and thumbprint to the pawn shop without any trouble (despite his growing notoriety).

On 25 July, 1997, Fernando Carreira, the caretaker of a houseboat docked at Miami Beach found evidence of an intruder on the boat and left to call the police. As he was leaving the boat, he heard a gunshot from within. Police quickly surrounded the boat and sealed off the area. After five hours of waiting, tear gas was launched into the boat. When no one came out and no activity was heard from within, SWAT-team members acted and entered the houseboat. Therein the SWAT team found Cunanan, dead and nearly naked, having shot himself in the mouth hours earlier.

There's a bit of a debate among experts in sociology and criminology as to whether Andrew Cuanan should be classified as a serial killer or a spree killer. Cunanan does fit the technical definition of a serial killer according to many organisations, such as the FBI, for having killed a certain number of people within a specific time frame, but most serial killers seem to have treated their slayings as they would sex. Rather than simply killing someone and moving on to the next victim, most serial killers have experienced each killing with a high amount of mental and physical intensity, even becoming sexually aroused and typically torturing their victims. Spree killers, on the other hand, are associated more with a kill-and-run type pattern to their slayings. What differentiates spree killers from mass murderers is that a mass murderer's victims are all in relatively the same area and killed around the same time.

Cunanan did torture one of his victims, Lee Miglin, but the others he finished off quickly with a gun. Serial killers, for the most part, are known for indulging in more sadistic methods of tormenting and killing their victims. There are exceptions to this such as David Berkowitz, largely regarded as a serial killer, who used a gun to quickly kill his victims.