Do rewards help capture the world's most wanted men?

The Libyan rebels have announced an amnesty for anyone within Col Gaddafi's "inner circle" who captures or kills him, and a $1.7m (£1m) reward. But how effective are bounties - and are they really paid out?

Here are some of the most high-profile rewards that have been on offer in recent history.

Qusay and Uday Hussein

Image caption A $30m reward helped arrest Uday Hussein (above) and his brother Qusay

The United States' set of 55 playing cards, issued in 2003 and depicting "the most-wanted members of the former Iraqi regime", has undoubtedly been one of the most visible reward campaigns.

Cards in the set were mostly senior members of the Baath Party or Revolutionary Command Council (RCC) - with rewards for help in catching many of the remaining fugitives.

Two of the first men to be caught were the aces of Clubs and Hearts, Saddam's sons Qusay and Uday Hussein - who were valued at $15m each.

They were killed in a villa in Mosul on 22 July 2003.

The informant who provided information that led to their hideout was given the largest US bounty payment to date, a total of $30m.

Terry Pattar, a counter-terrorism expert at Jane's Strategic Advisory Service, suggests the informant was probably inspired to come forward because Saddam Hussein's regime was "deeply unpopular, which gave people the motivation to inform".

"These kinds of rewards perhaps encourage people who are more likely to give information - where it's clear they'll be giving it to the side that is going to eventually win.

"It was clear the US were going to succeed in Iraq - there was no chance of the Baathist regime coming back - so there was less fear of reprisals and more chance of managing to claim the money," he says.

Saddam Hussein

Image caption Iraqi leader Saddam Hussein had a $25m bounty on his head

Top of the most-wanted pack, as the Ace of Spades, was Iraqi leader Saddam Hussein - with a $25m bounty on his head.

After a long manhunt, Saddam Hussein was captured near his home town of Tikrit on 13 December 2003, but it is believed nobody received payment.

In 2004, the BBC's Panorama programme revealed that the hiding place of the ousted Iraqi leader was given away by a relative - Mohammed Ibrahim Omar al-Musslit - who was also one of his closest bodyguards and his aide, known as "the fat man".

But because he did not willingly offer the information, but gave away the secret after being arrested and interrogated, the man who led the Americans to Saddam Hussein's secret bunker did not benefit from the $25m reward.

Ramzi Yousef

Image caption Yousef masterminded the February 1993 World Trade Center bombing

Arguably the biggest success of America's Rewards for Justice programme - which has paid more than $100m to more than 60 people who have provided information leading to the arrests of those involved in terrorist attacks - was the capture of Ramzi Ahmed Yousef.

Yousef masterminded the February 1993 World Trade Center bombing in New York City, which killed six and wounded more than 1,000.

Within hours of the bombing, he had escaped on a plane to Pakistan, later resurfacing in the Philippines where he was engaged in developing a terrorist plot to assassinate Pope John Paul II and blow up 12 US airliners in Asia.

In January 1995, police got one step closer to catching him when Yousef and one of his accomplices were forced to flee their apartment in Manila after a chemical mixture created a cloud of smoke which poured out of the apartment window.

Yousef fled to Pakistan, where he was eventually captured.

In February 1995, an informant went to the US Embassy in Islamabad, Pakistan, and provided information leading to Yousef's whereabouts. He was then extradited to the US and is now in prison in Colorado.

The informant was reportedly paid $2m.

Dr John Esposito at Georgetown University in Washington, DC says: "Rewards are a widely accepted way to get information and motivate others who normally wouldn't come forward to provide information. What you want is something that will push someone over the edge."

But he says that anonymity and trust are key to the success of a reward system.

"You have to be sure that people are protected. The fewest possible people who know, the better, because in order for the system to work well, there should be complete anonymity. Even in government circles, you want to keep it classified."

Martin Bormann

Image caption Martin Bormann was right-hand man to Hitler

Martin Bormann was a high-ranking Nazi official who preferred a low profile life. As right-hand man to Hitler, he was one of a few people with unlimited access.

At the Nuremberg trials following the war, he was indicted along with other Nazi leaders and found guilty for his leading role in the extermination of the Jews. He was sentenced to death in absentia because he was last seen on 2 May 1945 beside a German tank near Hitler's Berlin bunker.

And so the search began.

The British and German press became obsessed with finding him and over the years journalists and bounty hunters were sent on wild goose chases to find him.

There was speculation that the German government even offered a 100,000-mark reward for any information on the Bormann's whereabouts, but it was never claimed.

A Guatemalan peasant in 1967, and a 72-year-old German living in Colombia were both arrested, thought to have been Bormann.

Remains reported as Bormann's were found in 1972 and it was concluded he had indeed died on 2 May 1945, possibly due to suicide from poison.

Osama Bin Laden

Image caption Rewards for Justice offered a $25m reward for information about Osama Bin Laden

The al-Qaeda leader, believed to have ordered the attacks on New York and Washington on 9/11, was at the top of the US Most Wanted list.

The US Department of State's Rewards For Justice Program offered a reward of $25 million for information leading directly to his apprehension or conviction, but it is not clear as to whether any reward money has ever been handed out.

Additionally, $2m was being offered through a programme developed and funded by the Airline Pilots Association and the Air Transport Association.

US Defense Secretary Donald Rumsfeld said in 2001 he hoped offering a reward would provide an incentive for people to turn over those involved in the US attacks.

Some Congressmen have even suggested that any bounty money be paid to the families of 9/11 victims.

Bin Laden evaded the US and allied forces for almost a decade. He was shot and killed by a team of Navy Seals at a compound in Pakistan in May 2011.

But Pattar says it was not surprising that people had been less inclined to report his whereabouts.

"In Afghanistan there is still talk of the Taliban becoming part of government - it is not sure who will be on the winning side after 2014 - so I imagine people are much less willing to talk because of negative repercussions.

"People are also put off by the perception that it is difficult to claim the money, and by doubts about the sincerity of US forces, and how easy it would be to get out of the country," he says.