Spider-Man first encountered the criminal he later came to think of as "the Burglar" when he witnessed the man fleeing from TV station security guard Baxter Bigelow. Ignoring Bigelow's shouts asking Spider-Man to stop the fleeing felon, Spidey simply watched as the thief ran past him. However, later, when Peter was out, the Burglar broke into the Parker home and attempted to rob it, shooting Peter's Uncle Ben dead when he tried to stop him. When Peter came home and found out what happened, he tracked down the Burglar and easily defeated him. 
The Burglar had been the cellmate of the infamous depression era gangster "Dutch" Mallone. In the 1930's Mallone lived in New York City's Forest Hills section in the very same house that was now inhabited by Ben Parker and his family. Eventually, Mallone was captured at the same house by a force of Treasury agents led by the celebrated "untouchable" Elliott Ness and was convicted on tax evasion charges. It was long rumored that Mallone had hidden millions of dollars away somewhere. Mallone was sent from one prison to another, and finally, as an elderly man, he became the cellmate of the burglar. The Burglar heard Mallone talking in his sleep about where he hid the money. It was somewhere in his old house in Forest Hills. (unknown to the Burglar, however, the money was hidden in a box behind a wall in the House, but had long ago been devoured by silverfish.)
The Burglar next appeared in the hallway of a Manhattan Television studio just as young Peter Parker (still dressed as Spider-Man) stepped out of his dressing room. The Burglar had robbed the studio's office and was being chased by security guard Baxter Bigelow, who yelled at Spider-Man to trip the crook up before he could get to the elevator. Spider-Man refused to help, allowing the Burglar to make it into the elevator and escape.
One night, a few weeks after the Burglar and Spider-Man had crossed paths in the television studio, the Burglar broke into the Parker home while Peter was away making a personal appearance as Spider-Man. The Burglar took the Parkers by surprise and held Ben and May Parker at gunpoint. Saying that he needed her to show him around so he could find something, the Burglar grabbed May. Furious, Ben ordered the Burglar to unhand May and angrily reached toward him. Frightened, the Burglar shot Ben and fled. Ben Parker died.
Returning home, Peter Parker was told by policeman Bernard O'Brien that a burglar had killed his uncle and was now trapped by the police in the Acme warehouse at the waterfront. Infuriated, Peter donned his Spider-Man costume, went to the warehouse, and captured the Burglar. Upon seeing the Burglar's face, Spider-Man realized to his horror that it was same thief he had let escape at the television studio. Had he captured the Burglar then, Spider-Man told himself, his beloved uncle Ben would still be alive.
Spider-Man turned the Burglar over to police. Years later, the burglar, made a second attempt to find Mallone's treasure, held May Parker prisoner, and threatened to kill her if she didn't aid him. Spider-Man defeated the Burglar, who died of a heart attack brought on by his sheer terror of Spider-Man.