Experts say there are few tasks in law enforcement as difficult as trying to catch a serial killer.

In many cases, big breaks come only when a killer has made a sloppy mistake. Murderous fiends who have been brought down by their own errors include:

* Robert Hansen, whom authorities said killed at least 11 prostitutes in Alaska between 1980 and 1983, was caught after a would-be victim ran free.

* Harrison "Marty" Graham, who was convicted of strangling seven women, was nabbed after he was evicted in 1987 from his putrid-smelling North Philly apartment, where he stored his victim's remains.

* Jeffrey Dahmer, who was convicted of murdering 15 men and boys, was arrested in Milwaukee in 1991 after a potential victim fled his apartment and flagged down police.

* Ted Bundy, who admitted to murdering at least 30 women between 1972 and 1978, was caught driving a stolen Volkswagen Beetle in Florida in 1978.

* Gary Heidnik, who was convicted and later executed for murdering two women in a North Philadelphia basement where he had also held three other women captive, was arrested in 1987 after he let one of the captives briefly go free.

- David Gambacorta