Right now in New South Wales a total of $12.3 million in reward money is being offered by police in relation to 94 missing persons and murder cases.
The biggest reward among that pile of cash is $1 million – the largest inducement in the state's history – which police hope will lure somebody with information about the disappearance of William Tyrrell to come forward.
William was three years old when he went missing from his grandmother's house in Kendall, on the mid-north coast, two years ago.
"That's one million reasons why somebody that's out there that knows what's happened should come forward and talk to us, and do it soon," Police Commissioner Andrew Scipione announced on Monday, the anniversary of William's disappearance.
But how effective is a cash reward in helping solve a case like this? That's a difficult question to answer, and given that reward recipients generally stay anonymous, the data is hard to quantify.
"There's no particular stats on it because it's not something that is promoted often. There's an incentive to provide information to solve long standing crimes," Jimmy Singh of Sydney Criminal Lawyers told nine.com.au.
"It can lead to finding perpetrators, it can lead to finding evidence that police probably would not otherwise have. It absolutely can be very effective."
But rewards, particularly in NSW, are seldom paid out. According to Crime Stoppers, only about 6 per cent of eligible callers even claim a reward, and not a cent of the $12.3 million in the NSW kitty has been spoken for, despite many of the crimes going back decades.
Between 1989 and 2011, according to its website, NSW Police paid out a mere $139,500 in reward money – but that sum was scattered over 384 payments, averaging out at a measly $363.28 each.
That figure could have been higher by $500,000 if Paul Onions, the British backpacker who almost became a victim of Ivan Milat, had accepted the reward he was entitled to after his testimony helped put the serial killer behind bars.
Mr Singh says vexatious tips and potentially murky territory in the end game of criminal prosecution could be among the factors that keep the reward rate low.
"If someone's offering a financial reward for something there are potentially a lot of people out there (making reports) for an ulterior purpose," the lawyer said, adding that a paid witness can be a dicey prospect on the stand.
"Any information they give tends to incriminate that person," he said of those who give induced statements.
"That's not used against them to lay charges later on. But there's also the issue of that person then being required to give evidence later on in a trial…(and the defence is notified) they are giving evidence in return for money."
So how do police decide how much to pay? In Victoria, the numbers are crunched according to the severity of the crime and the prison sentence it carries.
Information leading to a life sentence for example, can come with a $1 million lure, all the way down to rewards of $50,000 - $100,000 for crimes that may only carry five-year sentences.
In the case of William Tyrrell, one of the most high profile missing persons cases in recent memory, the price looks to be right.
"If you've got information regarding William's disappearance and you've got concerns that you could be potentially complicit in the offence by concealing the offence, that offence will be negated the moment you come to police," Chief Inspector Gary Jubelin said on Monday.
"That's a big ticket item that you can consider if you have been sitting on this information."
If you know any information about an unsolved crime, call Crime Stoppers immediately on 1800 333 000.