The Hunt for America's Most Wanted Fugitives

The dragnet for escaped inmate and suspected murderer John McCluskey along with his girlfriend is now in its third week, and they seem to have simply disappeared.

The last credible sighting of McCluskey and Casslyn Welch, who authorities call a modern day Bonnie and Clyde, was on Aug. 6 in Billings, Mont.

Authorities are combing the rugged terrain along the U.S.-Canadian border of northwestern Montana, although according to the marshals the duo may already be deep inside Canada. A reward of $35,000 is being offered for any informaiton leading to the arrests of McCluskey and Welch.

VIDEO: One Escaped Convict Captured, Hunt Contiues for the OtherPlay
Manhunt: One Down, One to Go

Officials believe they may have dyed their hair or taken other measures to change their appearance since Welch allegedly helped McCluskey break out of an Arizona prison on July 31 along with two other convicts. The two accomplices have been recaptured, but McCluskey and Welch have eluded a massive dragnet.

The couple is believed to still be traveling together and still driving a car they were given in Phoenix, possibly by an accomplice.

"It is believed they are still driving the 1997 Nissan Sentra sedan (gold, gray, or tan in color). The Sentra originally bore Arizona license plate 620 PFV, however, the plate may have been switched," Richard Tracy of the Arizona U.S. Marshals said in a statement Monday.

Sightings have placed the duo from Amarillo, Texas, to Yellowstone National Park in Wyoming, according to U.S. Marshals. Police also believe a 60-year-old couple whose charred remains were found in a burned camper in New Mexico were killed by McCluskey and Welch before they took their pickup truck.

They are considered to armed and extremely dangerous.

While McCluskey and Welch have the headlines, there others that the marshals and the FBI are hunting. Here are seven of the country's most wanted fugitives:

A Look at Some of America's Most Wanted Fugitives

Eduardo Ravelo

Ravelo is one of the FBI's Top 10 Most Wanted

Eduardo Ravelo, one of the FBI's Top 10 Most Wanted Fugitives, is an alleged captain and hitman for the Barrio Azteca criminal enterprise. He is accused of racketeering, money laundering, drug trafficking and numerous murders since 2003.

Ravelo is believed to be in his 40s, according to the FBI, and goes by numerous nicknames, including "Tablas." He has a scar on his face and has ties in Mexico and El Paso, Texas, according to the FBI.

A reward of $100,000 is being offered for information leading to Ravelo's arrest, and he is considered armed and extremely dangerous. Anyone with any information is asked to contact their local FBI field office.

Jason Derek Brown

Brown is known for a flashy lifestyle

Jason Derek Brown, 41 is a flashy criminal known to show off a slew of high priced cars and boats and enjoys "being the center of attention." Brown is also fluid in French, has a master's degree in international business and is an avid skier and golfer.

He is also wanted by the FBI for allegedly murdering an armored car guard outside of a Phoenix, Ariz., movie theater in 2004 before fleeing with the cash.

Brown has ties in California, Arizona and Utah and is known to carry a Glock 9mm handgun, according to the FBI. A reward of $100,000 is being offered by the FBI for information leading to his arrest.

James "Whitey" Bulger

Although 80, Bulger is still thought to be armed and dangerous

The FBI has resorted to an unusual tactic in its effort to catch James "Whitey" Bulger, the infamous Boston mob boss who was convicted of 19 murders before going on the run for the last 15 years. It has put his wanted poster in a newsletter that is distributed to plastic surgeons.

Bulger, 80, is known to travel with his wife, Catherine Elizabeth Greig, 59. Greig, according to the FBI, has had numerous cosmetic procedures, and authorities say they hope the ad will spark the memory of any surgeons who have operated on her in the past or might in the future.

"James Bulger and Catherine could be anywhere in the world, and we're always looking for opportunities to find them," Special Agent Gail Marcinkiewicz from the FBI's Boston office told ABC News.

"The more people who see the pictures, the more opportunities we have to find them. We've never tried this through Plastic Surgery News, but this may be a very positive thing to do," Marcinkiewicz said.

A $2 million reward has been offered to anyone who helps bring in Bulger and Greig.

Nazira Maria Cross

Cross is accused of murdering her husband, and running over his grave

Nazira Maria Cross allegedly poisoned her husband in California in 2008, then drove him 60 miles into Nevada as he slowly died. After his death, Cross, 45, allegedly buried his body on a Nevada ranch before running over the grave several times with her car.

The FBI considers Cross, a native of Costa Rica, to be armed and dangerous.

Paul Merle Eischeid

Eischeid allegedly traded in life as a stockbroker for the Hell's Angels

Paul Merle Eischeid, 35, is featured on the U.S. Marshals' Top 15 Most Wanted fugitives. Known as the stockbroker turned Hell's Angels biker, Eischeid was a Charles Schwab broker before allegedly joining the motorcycle gang, according to the marshals. He is wanted on a slew of charges, and is a suspect in the gruesome murder of an Arizona woman.

U.S. Marshal Service Director John F. Clark said Eischeid is on the list for two reasons.

"First, the murder-and-mauling charge he faces is one of the most grisly in recent American criminal history. Second, Eischeid threatens an extraordinarily wide range of Americans," Clark said. "He's a former stockbroker who appears studious, clean cut, and personable, but he's a member of the Hells Angels gang. He is widely traveled and poses a violent risk to anyone with whom he comes in contact."

A $25,000 reward is being offered for information leading to Eischeid's arrest, and anyone with a tip can call the U.S. Marshals at 1-800-336-0102.

Daniel Andreas San Diego

San Diego is an alleged animals right's extremist

Daniel Andreas San Diego, 32, is an alleged animal rights extremist who FBI officials believe is behind the bombing of two office buildings in the San Francisco area.

According to the FBI, San Diego allegedly had a role in planting two bombs at the Chiron Corporation in August 2003, as well as a nail bomb that exploded at the Shaklee Corporation that September.

A reward of $250,000 is offered for any information leading to San Diego's arrest.

Semion Mogilevich

Mogilevich allegedly ran a $150 million investor fraud

One of the FBI's Top Ten Most Wanted, Semion Mogilevich was allegedly behind a multi-million dollar investor fraud scheme between 1993 and 1998.

According to the FBI, Mogilevich, thought to be in his early 60s and originally from Ukraine, funded a scheme that defrauded thousands of investors in the stock of a Canadian company, resulting in investor losses of more than $150 million.

A reward of $100,000 is being offered for any information leading to Mogilevich's arrest.