Listeners to RTé's Liveline probably didn't know it at the time, but Tuesday 1 May 2007 marked the completion of the transformation of Paul Williams from mere journalist to bona fide brand. The Sunday World crime editor was talking to Joe when one of the country's most notorious criminals, John Daly, phoned the show from his cell in the supposedly high-security Portlaoise Prison to have a go at Williams. The way that the veteran crime hack swatted away Daly's criticisms before asking the question that everyone was thinking – "where did you get a mobile phone in jail?" – made the programme one of the most compell­ing in living memory. The storm of public and political outrage following the incident reinforced Williams's reputation as the fearless hack ready to take on the criminals no matter what the consequences.

On Tuesday night, "Paulie's" latest book will be launched and hundreds of politicians, gardaí, celebrities and journalists will descend to pay their respects to the man who has been described, by Joe Duffy, as the "out-stand­ing journalist of his generation".

There can be no arguing that he is certainly the best known and one of the most successful. The Leitrim native moved to Dublin in 1984 and studied journalism in Rathmines College. Among his contemporaries there were the Sunday Tribune editor Nóirín Hegarty, editor of the Evening Herald Stephen Rae and Irish Sun editor Michael McEniffe. He was also friendly with well-known BBC journalist Orla Guerin. He was eager to get his hands dirty and dropped out after only a year when he landed a job at the Longford Leader. After learning the journalistic ropes, he joined the Sunday World in 1987 and began to focus on crime reporting, writing about the drug barons who were importing heroin.

But it was after the 1996 murder of Sunday Independent crime reporter Veronica Guerin that he really came to national prominence. The passionate way in which he articulated the national outrage over the murder exposed him to a new audience and he seamlessly took Guerin's place as the most high-profile investigative crime reporter in the country. Since then, he has led the way in breaking scoop after scoop and chronicling the crimes of countless gangsters, including Guerin's suspected murderer, John Gilligan.

Williams and the Sunday World led the way in giving nicknames to crimin­als in order to avoid the strict libel laws, and 'The Tosser', 'The Penguin', 'Babyface' and 'Fatpuss' all entered the public consciousness. But this tactic also led to criticism, with some arguing it glamourised these criminals and gave them a higher profile than they would otherwise have enjoyed.

Williams's rise has not all been plain sailing though. In November 2003, the journalist and his family were asleep in their home when a passing garda noticed a suspicious device under their car. The Williams family and 140 of their neighbours had to be evacuated while a controlled explosion was carried out on the hoax bomb. It is believed that the device was a warning from a major gangland figure to stop investigating his criminal activities. In his typically populist way, Williams responded to the bomb threat by saying, "I am not going to stop taking on these bastards."

He was one of the first writers to realise that the public's fascination with gangsters could benefit his bank balance, and Crime Wars is his sixth offering in 13 years. All his books have proven to be massive sellers. The General, which told the life story of arch-criminal Martin Cahill, was turned into a Hollywood movie, and last year came The Untouchables, a profile of the Crim­inal Assets Bureau, which was made into an award-winning documentary for TV3, with Williams as the presenter.

Crime has certainly paid for Williams – he lives in a €1m house in Rathfarnham with his wife Ann Sweeney (whom he met in his first job) and two teenage children. Williams (43) is a gregarious character who always has a story to tell and an anecdote to share. He is at his most comfortable holding court in a bar surrounded by close friends, many of whom are serving or former gardaí.

Among his inner circle are RTé broadcaster Joe Duffy (who will be MC at his book launch on Tuesday), defence minister Willie O'Dea, former garda commissioner Pat Byrne and retired assistant commissioner Tony Hickey. Williams is no shrinking violet; he is not afraid to tell people when he believes he has been slighted and prides himself on calling things as he sees them. He has crossed swords with close friends on a number of occasions and is sensitive about his image, sending legal corres­pondence to various newspapers over perceived inaccuracies over the years.

Williams has a reputation for being helpful and supportive to talented young journalists, but he is a jealous guardian of his position as top dog among crime journalists.

There have been many criticisms levelled against him over the years, chief among them being that he is little more than a cheerleader for the gardaí who steers away from reporting on the scandals which have blighted the force.

Williams has been with the Sunday World for 21 years and during that time, the paper has outstripped the Sunday Independent to become the most widely read in the country. There is little doubt that he is a significant factor behind this. In many ways Paul Williams is the World. Through clever marketing and his forceful personality he has transformed himself into a one-man brand. Last Sunday, the front cover of his new book was the main image on the paper's front page. He has become such a phenomenon that his stories these days almost take second place to his personal celebrity. Friends say that he is only too aware of this and has renegotiated his contract throughout the years to reflect his market value.

They say that imitation is the ultimate form of flattery, and Williams has recently appeared as a character – Paul 'The Hack' Williams – in RTé radio's popular comedy sketches Nob Nation. He is a fan of the humour and Oliver Callan, the comedian behind the skits, will also perform at his launch.

With gangland murders at an all-time high and the public's morbid fascination showing no sign of abating, it is safe to say that Paul Williams will be in the nat-ional consciousness for quite some time.