Son of Sam"
David Berkowitz

Calling himself "the Son of Sam" in a letter left at one of the crime scenes, Berkowitz claimed voices were ordering him to kill. Starting in the summer of 1976, Berkowitz went on a 13-month spree of impulse killings in New York City that left six dead and seven injured. The hysteria that accompanied his reign of terror was captured on film by director Spike Lee in The Summer of Sam, released in 1999. Berkowitz is serving six consecutive life sentences at the Sullivan Correctional Facility in New York State.

Ted Bundy

In 1975, Bundy, who was driving a stolen car, was arrested in Utah on suspicion of burglary. After his arrest, reports arose of connections between him and a local woman who had been kidnapped. In 1977, he was put on trial and convicted of murder. Bundy escaped from his Aspen, Colo., prison but was arrested again in Florida 6 days later. He ultimately confessed to murdering 23 women and was put to death in Florida's electric chair on Jan. 24, 1989. He could have been responsible for murdering as many as 100 girls and women.

Jeffrey Dahmer

His calm demeanor hid the mind of a psychopath. Dahmer appeared so normal that even after one of his victims escaped to a nearby hospital, he convinced two Milwaukee police officers to release the 14-year-old boy back into his care. He eventually confessed to killing 17 people. Dahmer lured victims to his apartment and slept with some after killing them. He said he dismembered others and ate some. In 1992, he was sentenced to serve 957 years in prison. He was killed two years later by another inmate.

John Wayne Gacy Jr.

A successful contractor, Gacy was considered a pillar of his community before his arrest in 1978. But his passive behavior was only a guise hiding a ruthless killer. When Chicago police finally caught on to him, he had killed and raped dozens of boys and young men in the Chicago area. Investigators found 28 bodies buried in the crawl space of his house and the surrounding yard. Another five bodies were recovered from a nearby river. He was given the death sentence and died by lethal injection on May 10, 1994.

Luis A. Garavito

Luis Alfredo Garavito apparently committed his first murder in 1992, but the hunt for the worst serial killer in Colombian history was not launched until 1998, when 25 bodies were found in the western city of Pereira. The victims - mostly boys between 8 and 16 - were found with their throats slit. The drifter, who has admitted killing 140 children across Colombia, said he has a history of mental illness and alcohol abuse and was beaten and raped as a child, according to published reports.

Unabomber"
Ted Kaczynski

Kaczynski, a Harvard-trained mathematician who became a forest recluse, pleaded guilty in January 1998 to mail bombings that killed three people and injured 23. Two killings were in Sacramento and the third was in New Jersey. Kaczynski, known as the "Unabomber," was not the typical serial killer. His attacks were motivated by his campaign against technology and were not sadistic or sexual in nature.

Anatoly Onopriyenko

"I killed 52 persons with these hands." Onopriyenko, a forester arrested in April 1996, admitted to killing people across Ukraine, claiming he was following an "inner voice." Some 42 of the killings were committed in the four months prior to his arrest. He is believed to be the worst serial killer in Ukraine's history. Ukraine's Supreme Court rejected an appeal to revise the death sentence passed on the country's most notorious mass killer in mid-1999.

"The Railway Killer"
Angel M. Resendez

Nicknamed "the railway killer" because his crimes took place near railroad tracks, Resendez was the object of an international manhunt. Wanted for the murder of nine women in three states, he finally surrendered in El Paso, Texas. The killings to which he eventually confessed were brutal beatings and stabbings that took place in the victims' homes and were sometimes followed by a sexual assault on the dead or dying people. He was convicted of first degree murder on May 18, 2000, in Texas and now faces the death penalty.

Dr. Harold Shipman

Shipman was convicted in 2000 of killing 15 elderly female patients by injecting them with heroin and was sentenced to 15 life terms. Subsequent inquests have ruled that five other patients also were killed. Police in England are currently investigating the deaths of Shipman's 62 patients, who authorities fear may have killed as many as 300 of the people he treated during his 24-year career.

There is no single profile for a serial or mass murderer, but those who are caught often paint a chilling portrait in jailhouse confessions and media interviews.

Experts caution that in many cases these ramblings can only be taken with a grain of salt. The killers may simply be repeating something they read, or in the case of Henry Lee Lucas, confessing to crimes they didn't even commit. Others give us an open window into the mind of the criminally insane.

Ted Bundy

"I haven't blocked out the past. I wouldn't trade the person I am, or what I've done - or the people I've known - for anything. So I do think about it. And at times it's a rather mellow trip to lay back and remember."

Bundy was convicted of three Florida slayings, including that of a 12-year-old girl. He confessed to more than 30 between 1977-78, and was executed in 1989.

Aileen Wuornos

Convicted of murdering six men while working as a prostitute along highways in central Florida between 1989-90, Wuornos was one of the nation's few known female serial killers.

"I'm a very kind person," she said in a 1991 confession, "but when I get drunk, I do stupid things. And if you're a hooker, and you get somebody who starts messing with you, then you get pissed off."

Wournos explained in an interview with the Orlando Sentinel, "I'm not a man-hater. [I am] so used to be treated like dirt that I guess it's become a way of life. I'm a decent person." In later interviews she has also said her sole motive was robbery.

"I'm one who seriously hates human life and would kill again," Wuornos wrote in a letter to The Florida Supreme Court asking to be executed. "So what's the point!" She was put to death by lethal injection on Oct. 9, 2002.

Thomas Lee Dillon

A sniper who chose his victims at random, Dillon terrorized residents of rural Ohio between 1989-92. He has confessed to five murders but is suspected of more.

He spoke of "an irresistible compulsion that has taken over my life" in a letter sent to the local Times Leader newspaper before his capture. "I knew when I left my house that day that someone would die by my hand. I just didn't know who or where. Technically I meet the definition of a serial killer, but I'm an average-looking person with a family, job and home just like yourself."

Henry Lee Lucas

Once considered one of the nation's most prolific serial killers, Lucas confessed to 600 killings nationwide but later recanted on most. His was the only death sentence to be commuted by President Bush during his term as governor, due to lingering doubts about the murder in question. He died in his prison bed of natural causes in 2001.

"Killing someone is just like walking outdoors," Lucas has said. "If I wanted a victim, I'd just go and get one." In a jailhouse interview he explained, "I didn't have no feelings about killing (him). It was just like I drink a glass of water."

David Berkowitz

A 'possessed' dog in the neighborhood "won't let me stop killing until he gets his fill of blood," Berkowitz has famously stated. He said he didn't want to hurt his victims, "I only wanted to kill them."

Known as the "Son of Sam" killer, he killed six people and wounded seven others between 1976-77 in New York City. He is serving six consecutive 25-years-to-life sentences.

Angel Maturino Resendiz

"Many will ask how I could do this while believing in God, and all of that," Resendiz said in his first media interviews. "It's not that I'm a person totally outside the system. I'm a person who is part of the system. When they killed those children in Waco, that affected me greatly."

Resendiz was sentenced to death for murdering a Houston woman, but has been linked by confessions and evidence to at least 12 other killings nationwide.

He described a "revelation" that told him to kill his victims, who he said had done nothing wrong to him. "I could feel that there was something bad there (in the houses of the victims). And after entering, I confirmed that yes, something bad had passed there ... something dark, something satanic, something malignant."

Killer Mistakes

Some of America's most notorious killers have been undone by their own careless mistakes. Over time, even the most meticulous plotters are likely to leave behind some scrap of evidence, reveal some key clue or just plain run into bad luck.

David Berkowitz
"Son of Sam" Killer
The man who terrorized New York City for more than a year in the mid-1970s tripped up when he parked his car illegally on the way to one of his killings.

A Brooklyn woman walking her dog on the night of the murder said she saw a car in front of a fire hydrant being ticketed and the owner carrying something in his outstretched right hand. She heard four gunshots, one right after the other, as she raced home in fear.

When she alerted police, investigators began tracing all cars given summonses in the area of the murder, and came up with Berkowitz's name in connection with a $25 ticket. He is now serving six consecutive 25-years-to-life sentences for the shooting spree, which killed six people and wounded seven others.

Ted Kaczynski
"The Unabomber"

Kaczynski went uncaptured during a series of mail-bomb attacks that killed three people and injured 23 between 1978 and 1995.

He'd sent a 35,000-word manifesto to media outlets, and the FBI encouraged the Washington Post and New York Times to publish it jointly in 1995. Portions from the Post were read by Kaczynski's younger brother David, who found the writings eerily similar to letters he'd received from Ted. He notified authorities, and Ted was arrested in rural Montana.

David received a $1 million reward for the Unabomber's capture in 1998, money he said would go to bombing victims and their families. Kaczynski is serving a life sentence in federal prison in Colorado.

Peter Sylvester
The Long Island Sniper

The 24-year-old ex-convict was an early suspect in the 1994 shooting spree that left one man dead and a woman injured. Police watching Sylvester's movements soon arrested him on a parole violation, but could not connect him to the shootings.

Then, a man who'd attempted suicide said he'd bought the gun from Sylvester. The gun was one of three stolen from a local taxidermist's shop; another of the guns was found in Sylvester's car.

Neither weapon matched evidence at the crime scenes, but police were able to track down the previous owner of the third gun, a .35-caliber Remington rifle. Bullet fragments lodged in trees at the man's house matched those used in the shootings. Sylvester confessed, and the rifle was found at his mother's home. He's currently serving a sentence of 30 years to life.

James E. Swann
The "Shotgun Killer"

Swann preyed on residents of two Washington, D.C. neighborhoods in 14 attacks that took place in 1993. He eluded a massive police dragnet for several weeks before claiming his final victim on April 19. He might have slipped past police again had an off-duty officer not noticed him running several red lights. The officer noticed that Swann's car matched descriptions tied to the shootings, and chased him into a parking lot. A still-warm shotgun was found inside the car.

The spree left four people dead and five others wounded. Swann was declared not guilty by reason of insanity and ordered confined to a mental institution.

Mohammed A. Salameh
Terrorist

The Palestinian immigrant's mistake was trying to get back his deposit for the rental truck that was loaded with explosives and destroyed in the 1993 bombing at New York's World Trade Center.

Salameh was arrested after he returned to the Ryder dealership in Jersey City, N.J., with police documents showing he had reported the vehicle stolen. Investigators had found vehicle fragments with an identification number matching the one on the van, and Salameh's involvement was confirmed after his rental papers tested positive for chemical nitrates, which is common to many explosives.

Asked why Salameh would have rented a truck in his own name, reported it stolen to police and the dealership and return twice seeking a refund of his $400 deposit, a senior law enforcement official at the time said: "Who knows? Just because he's a terrorist doesn't mean he's a brain surgeon."

Timothy McVeigh
Oklahoma City Bomber

After the bombing of the Murrah federal building in Oklahoma City, McVeigh was pulled over on an interstate highway north of the city for speeding in his yellow Mercury and driving without a license plate. Weapons charges, for the pistol strapped to his shoulder in a holster, were added later.

His connection to the bombing wasn't discovered until hours later, when he was matched to a police sketch of "John Doe No. 1," the suspected bomber. The act of domestic terror claimed 168 lives; McVeigh was executed in 2001.