Gabriel Luis Acosta / San Bernardino Sun via AP file

Redlands, Calif., police officers man a blockade near the entrance to the San Bernardino National Forest in Southern California on Tuesday during the manhunt for Christopher Dorner.

For six days this month, the FBI and the U.S. Marshals Service joined local enforcement in the desperate search for cop-turned-killer Christopher Dorner. The biggest manhunt Los Angeles has ever seen is now over, but there is no shortage of suspects in cold-blooded murders commanding the attention of federal agents.

The worst of them have been given spots on two lists: the FBI's Ten Most Wanted Fugitives and the Marshals Service's' top 15 fugitives. The rosters are a catalog of atrocities: a mother and two children with their throats slit, a little girl kidnapped and strangled, an armored-car guard ambushed after a pickup.

"It's a full-court press with these people," said Lenny DePaul, a U.S. Marshals commander who heads one of the agency's seven regional task forces devoted to capturing violent fugitives.

"There's funding, there's resources, there's travel -- no boundaries when it comes to a top 15 case."

The FBI's most-wanted each has at least one agent in a field office assigned to each case, bolstered by a special unit at headquarters in Washington which can "bring all the tools out of the toolboxes," said Jayne Challman, chief of the Violent Crimes Threat Section.

The suspects are on the two lists because the crimes are heinous, but also because the feds think extra attention and publicity will help catch them.

"I could name a thousand cases that could be on the top 15," said DePaul, who noted that the only way to get off the Marshals' list is in handcuffs or a coffin.

Since the FBI list was established in 1950, 497 fugitives have earned the dubious distinction, and all but 30 of them have been caught. The longest anyone has lingered is 28 years -- Victor Manuel Gerena, who is still wanted for a terrifying bank robbery in 1983.

DePaul said every lead on a top 15 case is followed up, quickly and exhaustively. Though many turn out to be dead ends, the marshals keep looking for the one that will let them cross another name off the list.

"They make mistakes," he said of the suspects. "Their resources run out, they communicate with someone, they slip up. Their luck runs out."

Here are some of the accused killers on the FBI and Marshals' list whose luck hasn't run out -- yet:

Andrew Neverson: He's a ladies' man with the "gift of gab" -- and a hair-trigger temper, investigators say. Neverson, 48, is wanted for the back-to-back murders of his sister and ex-girlfriend and has eluded capture for more than a decade.

Born in Trinidad, he moved to Brooklyn, N.Y., as a teenager, but was deported in 2000 after serving five years for shooting a girlfriend's uncle five times. His family helped him sneak back into the U.S. months later with a bogus passport -- a fatal mistake, according to the marshals.

U.S. Marshals

Andre Neverson

In 2002, Neverson allegedly killed his sister, Patricia Neverson, 39, with a gunshot to the head after an argument over money. Three days later, police found the body of Neverson's girlfriend, Donna Davis, 34, in a vacant lot. Police believe she was kidnapped and shot dead after breaking up with him.

The muscular 6-foot-2 suspect vanished for four months, then turned up with a gun, demanding to see his 2-year-old daughter, the feds say. By the time the cops found out, he was in the wind again. U.S. marshals, who put him on the most-wanted list in 2004, suspect he may have returned to Trinidad and could be supporting himself as a bouncer or by buying and selling cars.

Meanwhile, his New York relatives live in fear.

"I can never totally be safe," Akim Neverson, his nephew, told the New York Post in 2010. "When I'm walking, and it's dark or I'm in a crowd of people, I have to keep an extra eye out. I can't really ever be comfortable knowing he's out there."

Jason Derek Brown: He was a ringer for Sean Penn, with a back-story that a Hollywood producer would love. Brown was a Mormon missionary who earned a master's degree in international business before he morphed into something of a playboy, a club-hopping snowboarder and skier who drove fancy cars, the FBI says.

FBI.gov

Jason Derek Brown taken in 2004

In 2004, while buried under debt from living the high life, he pumped five bullets into armored-car guard Robert Palomares, 24, and fled with $56,000 in cash receipts from a Phoenix movie theater, authorities allege.

Agents have followed some tantalizing leads: a Cadillac linked to Brown found in Portland in 2005 and a sighting in 2008 in Salt Lake City by someone who had been in missionary training with him. The 43-year-old, who was added to the FBI's top 10 list five years ago, hasn't been seen since.

Investigators say the one-time golf-equipment salesman is highly intelligent, fluent in French and comfortable in international settings. His wanted poster notes that he "enjoys being the center of attention," a trait he's apparently managed to keep in check for the last eight years.

Daniel William Hiers Jr.: He's a fugitive-tracker's worst nightmare: an ex-cop who knows how to hunt, has martial-arts training and once said he'd rather die than go to prison.

Hiers, 40, who spent 11 years on the force in South Carolina, hid his depravity behind all-American looks and a shiny badge, authorities say.

Daniel William Hiers, Jr.

In 2004, the married officer allegedly befriended a single mom and then molested her 10-year-old daughter for months. He was arrested, suspended from his job and released on bond -- then failed to surrender to face new charges in March 2005.

His mother went looking for him at his Goose Creek house and got no answer. Instead, his wife of seven years, Ludmila, was found dead in the bedroom with a gunshot wound to the head. While on the lam, Hiers was charged with the 24-year-old's murder.

"I never imagined something like this could happen," the victim's mother, Sueli Cohe de Araujo, said in 2008, after traveling from her native Brazil to South Carolina for at a candlelight memorial marking the third anniversary of the slaying.

Hiers' Chevrolet Aveo was found in the border city of Laredo, Texas, three months after the murder, according to the Marshals Service. Weeks later, he was added to the most-wanted list, but purported sightings from Colorado to Toronto have not panned out.

Robert William Fisher: The crime was beyond horrific: a Scottsdale, Ariz., mother and two children with their throats slit from ear-to-ear, their home devoured by flames after a gas explosion. Just as disturbing was the revelation that Fisher, husband and father of the victims, was the suspect.

Robert William Fisher, photographed in 1999.

Investigators have called Fisher, 51, an "ultra-control freak." Police documents obtained by the Arizona Republic suggest the cardiac technician and former Navy firefighter may have snapped after his wife, Mary, got fed up with his philandering and domestic tyranny and started talking about divorce. He allegedly put a bullet in her head before blowing up the house to cover up the crime.

The last time Fisher was seen was the day of the slaughter, taking $280 out of an ATM. Ten days later, police found his car and the family dog in his favorite hunting spot. The FBI put him on its list in 2002 and the agent in charge of the case gets tips every week; all of them have turned out to be false leads.

An avid hunter and fisherman with an extensive gun collection, investigators believe the suspect could be surviving in the outdoors. They say he walks very erect with his chest pushed out because of a back injury, has a gold tooth on his upper left first bicuspid, likes to hang out at strip clubs, and favors Copenhagen chewing tobacco.

Alexis Flores: In the years after 5-year-old Iriana DeJesus was abducted, sexually assaulted and murdered, authorities had her suspected killer in their grasp twice. They just didn't know it.

FBI.gov

Alexis Flores, photographed in 2005.

It wasn't until 2007 -- seven years after the shocking slaying in Philadelphia -- that DNA tied Flores to the homicide, the FBI says. By then, he had already been deported to his native Honduras for crimes that pale in comparison.

"Now we have a name, now we have a face," the victim's mother, Lizasuain DeJesus, told NBCPhiladelphia.com in 2010, when Flores' name was added to the FBI list.

Her daughter was missing for five days in August 2000 before her body was found in a nearby apartment building. The preschooler had been strangled, police said.

Detectives began hunting for a drifter known only as Carlos, who had come to the neighborhood with a hard-luck story and been offered clothing and shelter, but had only a sketch to go on.

Flores, meanwhile, headed west. In 2002, he was arrested in Arizona for shoplifting. Two years later, he was busted for giving cops fake ID. That was a felony, and his DNA was collected and, the feds say, eventually matched to Iriana's case.

Those who knew the victim say they can't rest until Flores is captured.

It’s so tough on all of us. We just want justice," said C.J. Waddy, who was her preschool teacher and helps organize a memorial every year. "We want to get that phone call that they caught him. We want to know the person responsible for taking her away from us is getting everything he deserves."